It is my turn at the wok. My classmates leer over me, ready for a laugh. Every afternoon, we cook in the same teams of ten, gathered round a table, with two gas burners, a couple of woks, a chopping board and a few bowls and plates at our disposal. None of my particular friends are in my team, so I am obliged to work with nine young men who make strenuous efforts to avoid talking to me, and who are openly sceptical about the idea of a foreign woman becoming a Sichuanese chef. It is tedious, really. I have to fight to participate when we divide up the tasks, or else I find they all scarper to the store cupboards and the sinks without me. And I have to draw on all my reserves of bossy older sisterliness to engage them in the most trivial conversation. But, as always, the cooking itself makes me so sweetly happy that I don't really care about these inconveniences.

I flick on the gas tap and light the burner, ladle some oil into the blackened wok. My teammates smirk, and someone makes a witty remark under his breath in Sichuanese dialect which I don't understand. I just ignore him, and concentrate on the cooking. I have prepped my ingredients already: the snaking strands of pork, marinated in salt, soy sauce, Shaoxing wine and wet pea-starch; the ribbons of cloud-ear fungus; the pale-green slivers of lettuce stem; the pickled chilli paste; the garlic, spring onion and ginger. These are the ingredients of fish-fragrant pork, one of the most famous of all Sichuanese dishes.

When the oil is hot, I tip in the pork and stir-fry briskly as the slivers separate and whiten. Then I tilt the wok, so the oil pools at the side, directly over the flame, and add the pickled chilli paste, which stains the oil a deep, rich orange. I scatter in the ginger and garlic, stirring as they release their punchy fragrances, add the vegetables, mix everything together. Finally, I pour in the sauce, a mixture of sugar, soy sauce and vinegar, with a little starch to make it thicken and cling. Seconds later, the dish is finished, and I ladle it neatly onto a small oval plate. It has turned out rather well. The lazy strands of pork are tender and glossy, entwined with the dark fungus and the green lettuce. The red oil pools prettily around the edges of the dish, and it smells extraordinarily good. My classmates are disappointed by my success, and I feel extremely smug. Ha!

We all take turns to cook amid the jostling, subversive crowd. The boys are merciless in their criticism of each other, and of me. If anything goes wrong, they jeer and giggle. Every failure is jubilantly ridiculed. 'Too much oil!' 'It's all dried out!' 'The sauce has gone all sticky!' 'You stupid melon! (sha gua)' As each of us finishes, we troop off to the side of the room, where Teacher Lu is ready to assess our efforts. He sits there with his usual benign smile, but is precise in his criticisms. He ticks us off for careless or irregular cutting: 'Bu hao kan! (unattractive!) You've got thin slivers, thick slivers and chopstick strips, all mixed up together!' He can tell from the smell of the dish and the texture of the pork if the oil temperature was too hot or too cool, and he will taste to see how skilfully we have balanced the flavours. Today, he approves of my fish-fragrant pork. 'Bu cuo bu cuo (not bad, not bad),' he says.

Everything we made at the Sichuan Institute of Higher Cuisine was cooked from scratch. We had only rudimentary equipment: there were no mincing machines or food processors to save us time. If we were making pork balls, we had to pound the meat to a paste with the backs of our cleavers, teasing out with our fingertips every wisp of sinew. Eggwhites were whisked on a plate, with a pair of chopsticks. If we were using walnuts, we had to crack them open, soak them and then, laboriously, peel off their skins. ('Sichuanese cookery is so ma fan, so much trouble,' moaned one of my classmates, coaxing reluctant shreds of skin from a walnut kernel, dismayed at the prospect of a lifetime performing such tasks.) Some of the ingredients were still alive when we got them. We scrambled competitively to be first to collect our team's allocation of, say, thirty glinting crucian carp, which we had to clean in the sinks on the balcony, ripping their gills out and slitting their bellies as they jumped and twitched in our hands.

Unfortunately we are not allowed to eat what we cook, though we may taste it. The finished dishes are bagged up and sold from a table at the school gates to people in the neighbourhood. They are brave, these guinea pigs, because it's such a lottery: one day they might end up with an appetising supper, another day some ghastly, oversalted, stodgy mess. Reluctantly, I hand over my dish in its haze of delicious aromas, and go back to watch my classmates run the gauntlet of their peers.

Life in Chengdu in the mid-nineties appealed to this old longing of mine for the fundamentals of cookery. There were no shortcuts. Centuries-old methods of food preservation were used in most households. On sunny days, the backstreets were hung with cabbage leaves, which had to be half-dried before they could be rubbed with salt and spices and packed into jars to ferment. There were coils of drying tangerine peel on everyone's windowsills. And as the Chinese New Year approached, people started to smoke bacon and make sausages, hanging them out to wind-dry under the eaves.

As a child, my dream was to live in a cottage in the country, doing everything by hand. I wanted to grow my own vegetables, rear chickens, bake bread, make jam. Growing up, I was moved by the beauty of raw things, the silvery gleam of a fish in my hands, pink juices flowing from a cut beetroot. I enjoyed the kind of basic kitchen jobs that might seem boring to anybody else, like picking over a trayful of rice for stones, or topping and tailing green beans. Teenaged, I learned how to pluck and clean pheasants, and I made my own pastry and mayonnaise by hand. My family mocked me. 'When you grow up, you'll have machines to do everything. It's just a fantasy.' (I think I have the last laugh: years later, I still live without a television, a dishwasher or a microwave, and I still pluck pheasants and make pastry and mayonnaise by hand.)

There was only one thing that jarred for me in this prelapsarian world of cooking, and that was the use of monosodium glutamate, or MSG. Like most Westerners, I saw MSG as a nasty artificial additive, used only in junk food and trashy takeaways. In England, you never find MSG in a domestic kitchen, and it would be a public scandal if it was discovered in the store cupboard of a serious restaurant. Yet in China, every kitchen has its jar of MSG, tucked away amid the soy sauces and vinegars. Top chefs use it in their most acclaimed dishes, and it is treated as a normal seasoning at the Sichuan Institute of Higher Cuisine, the nation's top school for chefs. The Chinese even call this white powder wei jing, 'the essence of taste', and translate it into English as 'gourmet powder' (jing itself means not only 'essence', but also, among other things, 'refined, perfect, meticulous, clever, skilled, energy, spirit and sperm', which gives you some idea of what a wonderful word it is). There is no shame, in China, in using MSG.

At the cooking school, the pickles we used in our recipes were made in the traditional manner. There was a storeroom where waist-high clay jars lurked in a constant twilight. We lifted the inverted bowls that covered their mouths, and reached into the glowing scarlet of pickled chillies in brine, plucking them out with our chopsticks. When we wanted to lend a rich brown colour to a stew, we caramelised our own sugar in oil. There were no ready-made sauces, except for the slowly fermented chilli bean paste; we mixed them ourselves from the essential seasonings: sugar, vinegar, soy sauce and sesame paste in various combinations. I loved the alchemy of it, conjuring such basic elements into gold, my only tools a knife, a ladle, a board and a wok.

MSG is not a traditional ingredient in Chinese cookery. It was discovered in 1908 by the Japanese scientist, Kikunae Ikeda, who was intrigued by the intensely delicious taste of the broth made from kombu seaweed. In his laboratory, he managed to isolate its source, glutamates in the seaweed, and to their wonderful taste he gave the name umami, derived from the Japanese word for 'delicious'. His findings led directly to the industrial manufacture in Japan, and then worldwide, of MSG.

In the beginning, MSG was thought by scientists to be just a 'flavour enhancer', a substance with little taste of its own, but able to react with various savoury flavours to produce a pleasant sensory kick. Recently, however, biologists have found that human tongues have specialised receptors that pick up on the taste of MSG and a wider family of umami compounds, and that some of our brain cells respond specifically to the umami taste. This has led to growing acceptance that umami is not merely a flavour-enhancer, but a discrete 'fifth taste' in its own right, alongside the traditional quartet of sweet, sour, salty and bitter.

Although umami is associated with manufactured MSG, the taste is found naturally in many animal and vegetable foods, such as tomatoes, shiitake mushrooms and tuna. Their umami flavours come from the building blocks of proteins, amino acids and nucleotides, which include not only glutamates, but also inosinates and guanylates. These delicious molecules appear when animal and vegetable proteins break down, which is why processes such as cooking, ripening and fermentation intensify umami tastes. Many of the flavours adored by Europeans and Americans, like those of Parma ham and Parmesan cheese, owe their intensity to these umami compounds.

The Chinese have been using umami-rich products such as black fermented soybeans and related sauces for more than two millennia. Intensely flavoured broths enhanced by cured ham and dried seafood are among the staple flavourings of traditional Chinese cuisine. Cheesy fermented beancurd and the preserved duck eggs that so appalled me on my first visit to Hong Kong are both prized for their strong and complex umami tastes. In a sense, MSG is simply a continuation of this tradition.

In China, it's different. People like science. In a country where famine and hunger are recent memories, and drought and floods a constant threat to agriculture, it's not surprising that people are more open to the possibilities of genetic modification. Advances in food technology and the availability of new household gadgets like washing machines have only just begun to liberate women from the treadmill of domestic labour: it's too early for nostalgia about 'doing everything by hand'. And there are also historical reasons for a widespread trust in the benefits of science and technology.

But why did the Chinese take to the use of manufactured MSG with such joy when the West rejected it? I suspect it's partly because the Chinese generally have a positive view of science and technology. The kind of Europeans who love to cook and eat often regard science as the enemy: epicurianism tends to go hand in hand with a kind of back-to-nature fundamentalism. People like me think that advances in food technology are forced on humanity by corrupt scientists in the pay of greedy multinational companies. We expect that genetic modification will lead to ecological disaster; we are certain that pesticides will give us cancer. MSG, as a relatively recent, and artificial, seasoning, is inherently dubious.

When I first lived in China, traditional cookery, Tai Chi and Traditional Chinese Medicine were the norm, at least for the older generation. Now I meet young people who tell me they prefer sports to martial arts, pills to Chinese herbal medicine, and hamburgers to Chinese food, because they are 'modern'. In chefs' circles, the hot topic of discussion in recent years has been 'Western nutrition', which is seen as 'very scientific'. I wear myself out reminding advocates of Western nutrition that Westerners are totally confused about what they eat, and increasingly fat, cancerous and diabetic. We are drowning in scientific studies, I tell them! One month we are told that a glass of red wine a day will protect our hearts, the next month that it will give us heart attacks. Yesterday we were told to eat only protein and no carbohydrates, today we are told this will give us bad breath and kidney failure. Our food products are plastered with complicated information about salt and sugar content, calories, glycaemic indices -- but does anyone actually know how to eat? Many people just go home and shove some rubbish in the microwave.

In the late nineteenth and early twentieth centuries, the evident supremacy of the Western powers triggered a crisis in Chinese identity. Some thinkers and political activists came to see traditional Chinese culture as luo hou (backward), as a millstone round the neck of the nation: they despised it. The future, they thought, lay in Western science and rationality. The philosophical turmoil of the educated class was one of the triggers of revolution. A century later, these anxieties about the Chinese past, and green-eyed envy of the West, are as strong as ever. Ironically, just as the Western middle classes are losing their faith in science, and getting soggy with emotion over the holistic traditions of the East, the Chinese seem to be on the brink of ditching what's left of their own philosophical and technological heritage.

Contrast this with the traditional Chinese approach to food which is simple, holistic and, as far as I can see, remarkably beneficial. The older generation may not have figures and facts at their disposal, but they are masters in the art of balance in food. They know what to eat when they suffer from different kinds of illness and indisposition. They vary their diets according to the seasons, and their age. It's one of the things that impressed me most about China, this pervasive knowledge of how to eat well and healthily. 'Your traditional culture of food and medicine is one of the glories of Chinese civilisation! You should be teaching it to us!' I tell Chinese friends. They look at me, surprised and nonplussed, as if such a thought had never occurred to them.

MSG, of course, is very modern and scientific, which is clearly part of its appeal. But it must also have taken such a hold because of when it started to become widely available: the seventies. This was a period of great hardship in China, when meat was scarce and even grain was rationed. Suddenly, MSG offered the possibility of emulating the rich, savoury tastes of traditional stocks without using meat. It must have seemed like a miracle. Add a spoonful of MSG to a bowl of hot water, scatter in a few sliced spring onions, and you have a soup of sorts. Sprinkle some into a vegetable stir-fry and it will be fantastically delicious, as if you had added luxury ingredients like chicken oil or Yunnan ham.

At the cooking school, my classmates and I learned how to add MSG in small quantities to dishes at the final stage of cooking, to enhance their xian wei, as the Chinese refer to umami. We were taught to mix it into dressings for cold meats and vegetables, and to use it as a dip for appetisers. We were told to add MSG to almost everything. It was and is the same in restaurant kitchens, where MSG is used almost as widely as salt. Superior chefs might be scornful of those who use it as a substitute for decent stocks and fine ingredients -- I've heard them refer to such amateurs snidely as 'MSG chefs (wei jing chu shi)' -- but they all use it as a flavour-enhancer.

My friend Zhou Yu grew up in Chongqing in the seventies. During the Cultural Revolution, he remembers hearing the sound of gunfire as rival Red Guard factions battled for supremacy on the streets. As a teenager, when he was showing signs of the rare talent at the er hu or two-stringed Chinese violin that would make his career, he yearned for the delicious savoury powder that added a speckle of stardust to the humblest broth. He vowed that, when he had his own income, he would eat it every day. And so, when he finally enrolled in the Sichuan Conservatory of Music, he celebrated by buying four kilos of MSG.

The ubiquity of MSG in Chinese cookery puts me in a difficult position. Instinctively I loathe it, and I never use it when I cook at home. It's fake, it goes against all my principles. And I suspect that the excessive use of MSG in Chinese kitchens corrupts people's palates, deadening them to the pleasures of natural flavours. (Chinese chefs tell me they now have to use MSG, because their customers find everything tastes boring without it.) But is it any worse than refined salt or sugar, both of which are psychologically addictive and damaging in excess? There seems to be no conclusive proof that MSG is harmful to health: the existence of 'Chinese restaurant syndrome' has been widely discredited. Some scientists argue that MSG is a 'neuro-toxin' that overstimulates the pancreas and the nervous system, triggering diseases like autism, asthma, diabetes and obesity: but I'm not in a position to assess their findings myself, and I've seen little reflection of such theories in the wider MSG debate. Furthermore, all my great Chinese culinary heroes use MSG, and their food tastes delicious.

Frankly, I'm still confused about MSG, but I made the choice long ago not to use it in my own cooking. I don't find it necessary, since I buy good ingredients and make my own stocks. I'm also tired of being bombarded with MSG-laden food in Chinese restaurants which makes me thirsty and exhausts my palate. I prefer flavours that are gentler and more natural. For me, MSG is the cook's cocaine, a white powder that offers a turbo-charged intensity of gastronomic pleasure. But isn't life beautiful enough, without taking drugs?

I'm also conscious that, whether or not MSG really is a bad thing, Western prejudice about it has done untold damage to the international reputation of Chinese cuisine. And in my work as a sort of 'ambassador' for Chinese cookery, I realise that including it in recipes written for a Western readership would be shooting myself in the foot. So I stick to the traditional road, rejecting MSG just as I reject unnecessary kitchen gadgets and cable TV. Perhaps I'm still trying to prove something to my family.

Fortunately, my avoidance of MSG made absolutely no difference to my training as Sichuanese chef. No dish relies on MSG, and no special techniques apply to it. It is simply added to the wok with other seasonings. So I just omitted it, end of story. And given the overwhelming intensity of the natural flavours of Sichuanese cookery, I didn't miss it at all. My classmates regarded this as eccentric, but then they regarded everything I did as eccentric. Not using MSG was just the kind of thing you'd expect from a green-eyed alien like me.

MSG aside, the consideration of flavour was a crucial part of my Sichuanese culinary education. It was a thread that ran through the theory lessons that began each school day, the demonstrations given by Teachers Long and Lu after the mid-morning break, and the practical classes that occupied the afternoons.

Our teachers introduced us to the unsavoury aspects of the natural flavours of meat, poultry, fish and seafood, known collectively as yi wei, 'off-tastes', and more specifically as xing (fishy), shan (muttony), and sao (foul, uriney) tastes or odours. As chefs, my classmates and I had to learn how to refine or dispel these unpleasant tastes, and to bring out the delicious xian wei (umami flavours) that lay behind them. So we blanched our ingredients in boiling water, or treated them with salt, Shaoxing wine, crushed spring onion and ginger; and we discarded the bloody juices that leaked from meat and poultry. With foodstuffs where the yi wei were particularly heavy, like beef and mutton, eels and offal, we would add the wine and seasonings with a generous hand, and freshen up the final dishes with garnishes of coriander. Such techniques have been used in China for thousands of years: the chef Yi Yin, who lived in the sixteenth century BC, warned of the fishy, foul and muttony flavours of some ingredients, but said they could become delicious if treated properly.

But these fundamentals are common to all Chinese regional cuisines. It's the tiao wei, the mixing of flavours, that is the fundamental skill of the Sichuanese chef and the most fun to learn. Outsiders, Chinese and foreign, tend to stereotype Sichuanese cuisine as being simply 'hot and spicy'. It's a gross oversimplification. What really distinguishes Sichuanese cookery is its mastery of the arts of flavour. Sichuanese chefs delight in combining a variety of basic tastes to create dazzling fu he wei (complex flavours). A well-orchestrated Sichuanese banquet will titillate your palate in every conceivable way: it will awaken your tastebuds through the judicious use of chilli oil, stimulate your tongue and lips with tingly Sichuan pepper, caress your palate with a spicy sweetness, electrify you with dry fried chillies, soothe you with sweet-and-sour, calm your spirits with a tonic soup. It's a thrilling rollercoaster ride. So many and varied are the fu he wei of the Sichuanese kitchen that one might twist the words of Samuel Johnson and say 'If a man is tired of Sichuanese food, he is tired of life.'

As trainee chefs, my classmates and I studied a canon of some twenty-three 'official' complex flavours -- the equivalent, perhaps, of studying the composition of the 'official' French sauces. It wasn't a matter of exact measurements or precise ingredients, but of developing a sense of the character of each fu he wei, its balance of flavours, its strength and intensity. Take the fish-fragrant flavour (yu xiang wei) of our pork sliver recipe, for example, which derives its curious name from the fact that it uses the seasonings of traditional Sichuanese fish cookery (there is no actual fish in 'fish-fragrant' recipes).

'Fish-fragrant' is based on the mellow heat of pickled chillies, sometimes on their own, sometimes in combination with fermented broad beans in the famous Sichuanese chilli-bean paste, but always alongside the intense flavours of ginger, garlic and spring onion. Furthermore, it involves an element of sweet and sour. It's a classic fu he wei, engaging the palate simultaneously on several levels, and it's one of the most irresistible combinations of tastes you can imagine. Once you understand the mechanics of the 'fish-fragrant flavour' as a cook, you can apply it to all kinds of ingredients: cold chicken, slivered pork (the most famous 'fish-fragrant' dish), aubergines (that old favourite of mine), deep-fried chicken or seafood.

This emphasis on flavour makes Sichuanese a robust and confident cuisine. It doesn't rely too much on specialised local ingredients, like the cuisines of the eastern Chinese with their delicate water vegetables and acquatic creatures. You can't make a hairy-crab beancurd without a hairy crab, but you can make a 'fish-fragrant' dish or a 'numbing-and-hot' dish with anything. Perhaps this is why Sichuanese people are so open-minded and open-hearted compared with people in other parts of China: they don't have to worry that contact with the outside world will deprive them of their own identity. Just cover the outside world in a fish-fragrant sauce, and you will make it Sichuanese.

In contrast, there is the notorious ma la wei (numbing-and-hot flavour), which combines chilli heat with the tongue-numbing effects of Sichuan pepper. It can be quite overwhelming if you are not used to it, but it's not meant to be like slamming your tongue with a sledgehammer -- more like rousing the palate and awakening it to the other flavours of the meal. There are other permutations of the chilli-and-Sichuan-pepper mix, like hu la wei ('scorched chilli flavour'). Here, the two spices are sizzled in oil until the chillies are darkening, but not yet burnt and bitter: a marvellous taste. Throw in a bit of sweet and sour, and you have gong bao wei, the sweet-sour-scorched chilli combination found in the famous Gong Bao (or Kung Po) chicken. And so on.

As the one outsider in the class, I found myself not only learning the theory and practice of cooking, but also absorbing some Chinese ways of imagining flavour. On damp winter days, I knew I should eat more heating food than usual, so I spooned extra chilli oil on to my breakfast dumplings, and I discovered that sourness was refreshing in the sultry heat of summer. I learned how to say that someone who felt jealous in love was 'eating vinegar' (chi cu). And of course, I realised that 'eating bitterness' (chi ku) was the only way to describe the sorrows and hardships of existence. To learn the language of cookery in China was, in part, to learn the language of life. And as I went deeper into my culinary studies, I found that I was not only cooking, but also in some ways thinking, like a Chinese person.

When we took our dishes to Teacher Lu for assessment, he would tell us if we had the balance of sweet and sour tastes right for the li zhi wei ('lychee flavour') needed for crispy rice crust with pork slices, or if we had made it so sweet that it spilled over into the territory of a regular sweet-and-sour. Had we managed to create the right degree of harmonised chaos for guai wei ('strange flavour'), where sesame paste, sesame oil, soy sauce, sugar, vinegar, chilli and Sichuan pepper were mixed together into a sauce for cold chicken? If one seasoning was out of proportion, the flavour would jangle. So we sat there like chemists, scraping our little china spoons in our bowls, mixing and tasting, trying to come up with the perfect formula.

I remember days when the dishes my classmates and I made turned out completely differently, although we were all supposedly following the same recipe. With fish-fragrant pork, the colour of our oil varied from clear to deep orange-red, the fragrance of the ginger-garlic-onion trinity in some of our efforts was light and raw, in others so profoundly mellow it made you sigh. The pork slivers were supple as custard, or slightly chewy and shrivelled. I gazed at the array of dishes laid out on the workbench in front of Teacher Lu. 'Why do they all look so different?' I asked him.

'Huo hou,' he replied, smiling at my puzzlement.

Huo hou literally means something like 'fire-time', and it refers to the control of the degree and duration of cooking heat. The third pillar of the Chinese culinary arts, after the arts of cutting and of mixing flavours, huo hou is probably the most difficult to master. It cannot be taught in a clinical way, it is grasped only through experience, by trial and error. It's not surprising, therefore, that huo hou can also be used to describe the attainment of great skill and sensitivity in other arts, like calligraphy. Taoists traditionally used it, too, to refer to their practice of making pills of immortality.

Ultimately, though, huo hou was about a general sensitivity to the behaviours of hot oil and water, and to the ways in which they reacted with your ingredients. In the mid-nineties, most Sichuanese chefs didn't even have gas cookers, let alone thermometers. They were working with the ferocious heat of a coal-burning stove, of a design that hadn't changed much in two thousand years. There was no way of simply turning the heat up or down. Everything depended on the ability of their eyes and noses to function like military radar, picking up on every change in the micro-environment of the cooking pot.

At the cooking school, we were taught about the different types of flame: the intense heat and dazzling light of the high flame (wang huo); the vigour of the strong or 'martial' flame (wu huo -- the character wu is the same as that in wu shu, the martial arts); the gentle swaying of the 'civil' flame (wen huo -- the character wen carries connotations of culture and literature); and the pale-blue glow of the tiny flame (wei huo). We didn't use thermometers, but we had to become familiar with the Sichuanese scale of oil temperatures, which ran from one to eight cheng.

The beauty of huo hou, and its relationship with tiao wei, are best expressed by the legendary chef Yi Yin, again, lecturing his king on the art of cookery in the sixteenth century BC:

So, my classmates and I had to learn to recognise when the oil was hot enough to coax out the deep-red colour of the chilli-bean paste in our fish-fragrant pork, but not so hot that it would scorch it; when it was hot enough to set the velvety starch-and-water gloss on slivers of pork, but not so hot that the slivers would be dry and chewy. Garlic had to be sizzled to unlock its richness of flavour, but not for so long that it became bitter. As soon as we could see bubbles like 'fish-eyes' rising in our syrups, we had to remove the pan from the heat. Huo hou is the key to se xiang wei xing (colour, fragrance, flavour and form); it is the key to everything important in the Chinese kitchen.

Among the five tastes and three materials, the nine boilings and nine transformations, fire is the modulator. At times fierce, at times gentle, it eliminates fishiness, removes foulness and dispels muttoniness. Thus the control of fire is fundamental to nurturing the inherent qualities of all ingredients. Harmonious blending depends on the sweet, the sour, the bitter, the pungent and the salty. But as to when each is added and in what quantity, this is a matter of extremely subtle balancing, for each has its own effect. The transformations that occur in the ding [cooking pot or cauldron] are so supremely wonderful and delicate that the mouth cannot express them in words, nor the mind comprehend them. They are like the fine-tuned skills of the archer and the charioteer, the fluctuations of yin and yang, the passing of the seasons.

During the months I spent at the cooking school, my life in Chengdu settled into a delicious routine. I would rise early in my worker's flat near the university, and cycle across the city, picking up a bowlful of rice porridge or dumplings in chilli sauce for breakfast on the way. Familiar shopkeepers and street vendors would greet me as I passed. 'Chu shi, ni hao! Chef! Hello!' some of them would say (used, by now, to my sniffing and tasting, my incessant culinary questions). At school, I put on my chef's whites, tied back my hair, unwrapped my cleaver, and spent the day in a kind of kitchen bliss.

The culinary expositions of Yi Yin were recorded by a merchant called Lu Buwei in an essay entitled 'The Root of Tastes' (ben wei pian), written in the third century BC. It is perhaps the world's oldest extant gastronomic treatise. Yet much of what it says, astonishingly, is still relevant in the twenty-first century Chinese kitchen.

Late afternoons, I cycled back to the university district, more slowly this time, savouring the pleasures of the backstreets. Often I would be distracted by a chance conversation, and stay out until late. Sometimes I dropped into the foreign students' building, where I still had a few friends, and we would go out for dinner or drinks in the 'Old House', a revolutionary new bar that had opened in one of the timber-framed cottages just outside the university. In my second year in Chengdu, we no longer had to drink watery beer or Great Wall wine: the bar owners had acquired a stock of imported spirits, so even cocktails were possible.

Sometimes I threw dinner parties in my flat, testing my latest recipes on Bamboo Bar veterans like Davide and Pasha, or making gnocchi with the Italians. By Western standards, my flat was a grotty place to live. It was drafty and damp in winter; hot and infested with mosquitoes in summer. Laundry, hung out on the balcony for more than a few hours, became grey with fallout from the polluted sky. My mattress and bedding never seemed to be entirely dry. Strange creatures lived in the bamboo furniture; I could hear them munching quietly at night. Fat cockroaches patrolled the kitchen: every evening I went hunting with my spatula, splatting them against the tiles. Occasionally a rat paid a visit, too, and I found myself devising a trap made from a bra, a tape cassette, a plastic basin and a heavy dictionary (amazingly, it worked). But after more than a year in China, I was so besotted by the country that such minor deprivations didn't bother me at all.

By now I enjoyed dipping into expatriate life. In my first year in Chengdu I had wanted life to be as Sichuanese as possible. But now that I was spending each day immersed in China, my ears ringing with Sichuanese dialect and twenty-five different expressions for 'fry', nothing was more sweetly relaxing than sipping a gin and tonic with a bunch of other foreign students in one of the Westernised drinking places that had begun to spring up here and there.

Six days a week at the cooking school were not enough for me. In my free time I sought out restaurants and snack shops I hadn't visited before, and begged them to let me study in their kitchens. Sometimes I had to prove my mettle before they agreed. 'So, you're a trainee chef, huh?' said the owner of a beancurd restaurant in Leshan, a city near Chengdu known for its giant Buddha statue. 'Go on then, make us a dish.'

So I rolled up my sleeves, borrowed some chef's whites and a cleaver, rummaged around in the kitchen for the ingredients of Pock-Marked Mother Chen's Beancurd (ma po dou fu), and then cooked it, surrounded by twenty young chefs, who had all abandoned their work stations to gawp. When they had seen that I could make a reasonably decent ma po dou fu, the boss gave me immediate permission to hang around in the kitchen for as long as I pleased.

The manager of the famous Long Chao Shou snack restaurant in Chengdu, peering at me over his glasses, agreed to take me on as an ad hoc student. 'You are very lucky,' he said, 'I have a daughter who is studying in Canada, so I am sympathetic to your desire to understand another culture.' It was typical of the spontaneous generosity of so many people I met in China. The manager summoned his head pastry chef, Fan Shixian, and asked him to give me a free rein in the kitchens.

Master Fan turned out to be one of the most delightful chefs I'd ever met, and a treasure trove of information on Chengdu street snacks. I spent days in the restaurant, not only during my time at the cooking school, but also when I returned to Chengdu in the following years. There I learned the arts of the 'white board' (bai'an), as they call pastry-making in China (the other branch of cookery is known as the 'red board', hong'an). I sat for hours with the gossipy wrappers of the famous Long ('dragon') wontons, many of whom had been there for decades, as they turned out hundreds and thousands of dumplings. I learnt how to stuff glutinous riceballs with black sesame paste and to wrap 'cockscomb dumplings'. I made a mess as I tried and failed to master the knack of making bao zi, the little steamed buns with twirly tops, but no one seemed to mind. They just looked at the tangled rags of dough and minced meat I produced with good-natured smiles. Master Fan told me stories, made me laugh, and taught me how to make delicate zheng zheng gao (literally 'steamed steamed cakes' -- it sounds lovely in Chinese -- made from ricemeal and candied lotus seeds) and other rarely seen, old-fashioned snacks. The staff at Long Chao Shou took to calling me, teasingly, Master Fan's 'foreign apprentice'.

Sometimes you can see that my notebook has been taken over by someone else: an old woman listing remembered delicacies from her childhood, a chef writing out the names of some obscure ingredients, a noodle-shop acquaintance directing me to a favourite restaurant. (The work always feels like a collaboration, not mine alone.) Some notebooks cover a period of a month or two. Others, written feverishly during a period of intense learning, are filled in a matter of days. And it's not all about food, either. When I'm in China, these notebooks are my life. They contain train times and shopping lists, records of anxieties and inspirations, dreams and memories; descriptions of the view from a train or the swishing sound of bamboo in the wind.

My kitchen notebooks from that time are smudged and stained, splattered with cooking oil and batter. The words strewn haphazardly over their pages are written in a mixture of English and Chinese characters. It was often easier to write in English, but I had to use Chinese when I wanted to be precise about the name of an unusual vegetable, or to record one of the countless untranslatable cooking terms. There are also sketches and diagrams, reminding me how to wrap a new kind of dumpling, garnish a dish, or cut up a soaked dried squid. In some places there are herbs or flowers flattened between the pages, restaurant namecards, tickets for a Taoist temple or a train.

Most importantly, my notebooks are filled with recipes. Daily, I stood at the wok or pastry board, watching, writing swiftly in a mixture of Chinese and English, whichever was fastest at any particular moment. I became astute at judging quantities by eye. A tablespoon, a rice-bowlful, a handful: I knew my own measures by then.

Chengdu, meanwhile, was changing at surreal speed. One week I would be cycling through a district of old wooden houses on my way to school; the next, it was a plain of rubble, with a billboard depiction of some idealised apartment blocks overhead. Narrow crossroads metamorphosed suddenly into vast open junctions. Familiar landmarks just disappeared. It was like a dream, in which familiar places appeared to me, unmistakeable in their identities and yet strangely unknown. Luckily, I have inherited from my father an internal Global Positioning System that is very reliable, so I always knew where I was going, even if I couldn't physically recognise my location.

When I first knew Chengdu, there were only two high-rises in the city -- the Minshan Hotel and the People's Department Store -- and even they weren't very high. Now, new buildings were sprouting up like bamboo shoots after rain. All too often, I found myself sitting in a peaceful teahouse in a leafy alley, sipping tea and nibbling watermelon seeds, lost in the mellow atmosphere of cards and conversation, only to glance up and find that there was an immense skyscraper looming up over the wooden rooftops. 'Where did that come from?' I asked myself. A whole new city, futuristic in its gleaming ambition, was rising up around me, as if by stealth.

On the one hand, all this destruction was a tragedy. It felt like a personal tragedy for me, to fall in love with a place that was vanishing so quickly. My culinary researches began as an attempt to document a living city; later, it became clear to me that, in many ways, I was writing an epitaph. It also felt like a tragedy for the people of Chengdu, although they didn't yet recognise it. To start with a city so charming and distinctive, and to replace it with one that might be anywhere in China -- what a waste.

One of my favourite streets, Upper Heavenly Peace Street, which lined the southern bank of the Brocade River, was eaten away, day by day, by the demolition crews with their sledgehammers. First, the Chinese character chai, 'demolish', was chalked up like a sign of hopeless disease on the walls and doors. The teahouses and small shops closed. The old houses were reduced to skeletons, and then just stacks of timber on the ground. Household by household, people were shunted out to apartment blocks in the suburbs. When the last house was about to fall, I stole as a souvenir the sign which bore the name of the street (it now hangs in my flat in London).

On the other hand, there was something so vital and optimistic about China in the nineties. Gone was the utilitarianism, the sexlessness, the uniformity and the stultifying boredom of the tail-end of Chinese communism. The whole country was mobilised for action, moving forward by the collective will of 1.2 billion people. In England we agonised over the demolition of every old shack; in Sichuan, they just went ahead and flattened whole cities! You had to admire the brazen confidence of it, the conviction that the future would be better than the past.

So though my heart ached as I cycled through the ruined streets, I was simultaneously buoyed up by this dynamic optimism. I was in a state of flux too, my life was changing. I was rediscovering my creativity, forging fantastic friendships, shedding skins like a snake.