Hong Kong helped me to cross the border gently. It was China in some ways, but in others it wasn't. I could meet English friends for a cocktail in the Captain's Bar at the Mandarin Oriental, or I could watch live fish being dismembered in the Wanchai wetmarket; I could windowshop in the glitzy designer boutiques of Central, or lose myself in the feverish backstreets of Kowloon. I remember, on that first trip, entering a Chinese temple, the Man-Mo, in the old Chinese trading district of Sheung Wan. In the red-glowing, gold-gleaming, cavern-like interior, old ladies shook out their fortune-telling sticks and candles flickered. The strange gilded statues and smouldering coils of incense brought me out in goosepimples. But then I was able to take a taxi back into a more familiar world, meeting Sebastian and his girlfriend for dinner and English conversation. By the time I boarded the train that ran to the border with China proper, my fear had abated and I was ready to face the Mainland for the first time.

When I finally left Hunan, I stayed for a few days with some English friends in Hong Kong before flying back to London. I felt completely disorientated. I didn't know how to express myself and had forgotten how to behave like a normal English person. My friend Rob, who I have known since we were teenagers, and his wife Leslie helped me to ease myself out of my Chinese life.

In my years of travelling back and forth, I have come to think of Hong Kong as a kind of decompression chamber, a halfway house between home and China. It's been like that for me ever since my first visit, when I stayed with my cousin Sebastian in his apartment in Wanchai, on Hong Kong Island. Then, I was so terrified of my impending trip to China that I wondered if I could go through with it. I woke up every morning and looked through the window towards the Mainland, cold with fear.

Sebastian sat me down and told me everything that had happened while I'd been away: Oasis, Brit Pop, the National Lottery. And there was this new thing, he said, the Internet, that everyone was talking about. It was going to change the way we did everything. Shell-shocked by the sudden assault of news, cars, and Western advertisements, and the frantic pace of life in Hong Kong, I didn't really understand what he was talking about.

Three years later, on my way back from Chengdu at the end of my cooking course, I stayed with Sebastian again. Once more, I was in a state of potentially traumatic transition. For eighteen months I had been completely immersed in China, and had had very little contact with anyone at home, even my family. My perfect Oxford English was going to seed, because I had become used to speaking with people for whom English was a second language. In the Sichuan University dormitory, we had coined our own lingua franca, a mixture of English and Chinese with a bit of Italian and French thrown in. So I'd picked up all kinds of English phrases and neologisms that weren't really English, and my syntax was often a little foreign. I was badly dressed too, as I remember, with my army boots and cheap Chinese clothes. I felt like a peasant, completely out of touch with the slick modernity of Hong Kong.

When I haven't visited the Hong Kong decompression chamber on my way into deepest China, or at least spent some time in the lesser decompression chambers of Shanghai or Beijing, I have been struck with the bends. Flying direct from London to Changsha, for example, pausing only to change planes in Beijing, is a disaster. I feel uprooted and horribly confused every time. My tongue gets lost in a linguistic soup of English, Mandarin and dialect, and I find it hard to function socially for at least a couple of days. Hong Kong gives me the space to brace myself on my way into China, and to collect my thoughts and impressions on the way home.

My heart was heavy that week: leaving Sichuan had wrenched me. I stood one sunny afternoon in a secluded spot on the shore of the Tai Tam reservoir on Hong Kong Island, practising the qi gong movements I'd learned from my elderly teacher in that temple garden in Chengdu, trying to create a sense of continuity between the present, the immediate future and the life I was leaving behind. By the time I finally arrived at my parents' home in Oxford, I was ready to do what felt like stepping on to dry land again, after years at sea.

It works like this because everybody there is on the brink, like the place itself. My Hong Kong friends know what it's like to be juggling cultures on a daily basis. We can all swing either way, East or West, and we eat ambidextrously. In conversation, there is much that doesn't need to be explained, which is a huge relief. And Hong Kong is multicultural and international in a way that China still isn't. Even the taxi drivers speak a mix of Cantonese, Mandarin and English.

Sometimes these days, when I'm in a totally English environment -- a Fulham dinner-party scenario, say -- I feel like a foreigner, with my altered perspectives and traveller's tales. And in China, of course, I'm all too often still a big-nosed barbarian. But Hong Kong has been a hybrid ever since the British Crown wrested the unlikely island, with its deep and sheltered harbour, from China at the end of the first Opium War in 1842. Hong Kong people will choose, in an evenhanded way, whether to have croissants and Italian coffee or steamed chickens' feet with oolong tea for breakfast. They might go out for a bit of 'soy sauce Western food', or shop in a delicatessen that sells both dried abalone and Spanish membrillo. Everybody dips their deep-fried prawn dim sum in salad cream; their beancurd rolls in Worcestershire sauce. To visiting tourists this seems like a bastardisation; in Hong Kong, it makes perfect sense.

I first met Rose through some old friends who thought we might get along. And although at first it seemed as though we might have little in common -- Rose is a slick, international businesswoman after all, while I am a writer living in a dodgy part of East London -- we never run out of things to say. Because despite her appearance -- as petite and delicate as a fawn, and always impeccably well dressed -- Rose is a gourmet extraordinaire and a restaurant sleuth.

Whenever I'm planning to visit Hong Kong, I email Rose, and before the day is out, I'm at the receiving end of the first of a volley of replies, each one outlining suggestions of yet more restaurants and food shops to visit, delicacies to try, and food people to meet. Rose is a social chameleon, like many glamorous and well-heeled Hong Kong Chinese. Raised in Chicago by her Chinese parents, she speaks fluent English, Cantonese and Shanghai dialect, and passable Mandarin. She is equally at home in Chinese or international society, and with Chinese or Western food. One weekend she will be flying to Barcelona for dinner at the world's most exclusive restaurant, El Bulli, the next she will be crammed into a tiny upstairs room in Sheung Wan, eating raw crabs with her fingers and chomping her way through a Chiuchow stewed goose with garlic vinegar.

At home, you might find her tea-smoking her own oysters, sautéeing foie gras, or preserving osmanthus blossoms with salt and sugar. And whenever we meet in London on one of her globe-trotting business trips, she takes out of her elegant designer handbag a stash of Chinese goodies that she has brought especially for me: dried sea-moss and salted bamboo shoots from Shanghai, perhaps, or some special shrimp-and-chilli paste from Hong Kong.

Soon after our first meeting some five years ago, Rose arranged a Sunday lunch for our mutual friends and me at the Ningbo Residents Association restaurant. It was the kind of restaurant I could never have found on my own, tucked away in an office building and officially open only to the association's members. Rose ordered for us all in fluent Shanghai dialect, and the meal was a revelation. There were smoked eggs, their yolks like liquid gold; tiny clams steamed in a delicate, savoury custard; braised meatballs with bamboo shoot and shiitake mushrooms; chopped Indian aster leaves with dry beancurd and sesame oil; a scrumptious mash of broad beans with preserved greens and dried scallops; and, most remarkable of all, cold, raw mud snails steeped in sweet Shaoxing wine, their shells so thinly crisp they could be eaten whole. Afterwards, we filled up on sesame flatbreads and sticky rice-cake stir-fried with bamboo shoot.

It is testament to the diversity of Chinese cuisine that after more than ten years of dedicated research, I encounter new ingredients and new dishes not only every single time I visit the country, but often every single day. Even in Chengdu, which I know better than anywhere else in China, I am constantly surprised, and in Hong Kong, which I dip into every couple of years, the novelties flow thick and fast. Of course, it helps to have friends like Rose, who have their noses to the ground, sniffing out all kinds of delicacies hidden like truffles in the back alleys. By now I associate Hong Kong with these little gastronomic expeditions to basement delicatessens, teeming wet markets, restaurants in unlikely places, and tea shops in the backstreets of Sheung Wan or Central.

One of the places Rose introduced me to was the Lin Heung teahouse on Wellington Street, a rare survivor of the old teahouse culture of Hong Kong. I went there one morning for breakfast and warmed to it immediately. Outside, a woman was laying out the day's newspapers on a stand; inside, at just after 6 a. m., it was already busy, and the air hummed with Cantonese chatter. Most of the customers were elderly or middle-aged working men. Some sat alone, engrossed in the papers as they slurped tea and ate their breakfast; others gossipped with their friends. Bleary-eyed after my early rising, I found a perch at one end of a glass-topped table, and a waiter swiftly brought me my bowl, teacup and spoon, and a pot of musty pu'er tea. Soon waitresses were passing by with their trolleys, calling out the names of dumplings and other titbits. One lifted the lids of towers of small bamboo steamers to offer me fluffy buns stuffed with pork, and small dishes containing folds of tripe. Another had sticky rice with chicken, wrapped in fragrant lotus leaves. The tea-waiters rushed around with their kettles, replenishing teapots and bowls. Every few minutes, more customers arrived, and the clamour of conversation grew louder, mixing with the clatter of teacups.

Lin Heung is a rough-and-ready sort of place, with a worn tiled floor, metal spittoons, and ceiling fans whirring away in the corner of your eye. The walls are a clutter of framed calligraphies, and red plastic boards listing the dishes and dumplings on offer. One of my neighbours at the table that day, Mr Wong, fifty years old, had been coming almost daily for four years, to wake himself up before he clocked on for his job as an office cleaner. 'The tea is good, the water is good, and the boss is a smart man, he doesn't cheat us, he knows how to keep everyone happy,' he told me as he prodded the pile of Dragon Well tealeaves in his cup. His friend Mr Lau, eighty-three, said he had been a regular for fifty years. 'I come every day,' he told me, 'and some of the staff have been here for decades, too. Nothing changes, including the quality of the food, that's why I keep on coming.'

Lin Heung, or 'Lotus Fragrance', was founded in the 1920s, although it has moved several times from its original location. The first such teahouses opened in Hong Kong in the 1840s, but they began to flourish only after 1897, when the British authorities abolished their night-time curfew for Chinese people. From the 1920s until the 1940s, they sprang up all over the territory, and they acquired a vital social function in the post-war economic boom. Whole families were then living in cramped accommodation, sharing apartments with limited cooking facilities, or even no kitchen at all. Teahouses were cheap and convenient, as much for family meals as entertaining guests or discussing business. Some became known for particular trades, like the Kam Kong restaurant, frequented by dealers of watches and gemstones; others for their board games or musical entertainments. Visiting a teahouse became so central to Hong Kong life that people began to greet one another by asking, 'Have you had tea yet?' instead of the more traditional, 'Have you eaten?'

The har gau, or fresh prawn dumpling, is the best-known of the delicate steamed dumplings, and one of the most perfect when properly made. A dim sum cook will tease the white wheatstarch dough into a perfect circle with the flat of a cleaver blade, and then wrap it around whole prawns, lightly seasoned and mixed with a scattering of crunchy bamboo. After a swift steaming, the faint pink of the prawns glows through the pearly translucence of the wrapper, with its neatly pinched edge. The prawns are simultaneously crisp and tender, the wrapper soft and glutinous in the mouth. Cheung fun, sheets of slithery rice pasta wrapped around deep-fried doughsticks, barbecued pork or fresh prawn, and served with a drizzling of sweetened soy sauce, are made by pouring a thin riceflour batter on to a sheet of muslin, steaming it, and then wrapping it around the chosen stuffing with a few flips of a spatula blade. Steamed char siu buns are soft and fluffy, their white dough breaking open into a smile of barbecued pork in a savoury-sweet sauce.

While the teahouse ritual is known as yum cha ('drink tea'), the dumplings and other 'small eats' that are traditionally served are known collectively as dim sum, the Cantonese dialect form of the Mandarin dian xin. Dian xin is a curious term that defies direct translation into English, but means something like 'touch the heart'. It dates back at least to the Song Dynasty, when historical sources mention it as a name for the snacks customarily served for breakfast. Though dian xin are eaten all over China, it is in Hong Kong and the Cantonese south that they are most dazzling and abundant.

Booming properties prices and competition from restaurants spelled the end of the heyday of the Hong Kong teahouses. ('If it doesn't move, build on it', Hong Kong people quip). Their vast, sprawling premises were knocked down and replaced by skyscrapers; some teahouses moved to new locations, but most of them closed down for good. These days people flock to Lin Heung for a glimpse of the past, or the smarter Luk Yu teahouse nearby in Central. Luk Yu, named after the Tang Dynasty scholar who wrote a treatise on tea in the eighth century, was founded in 1933 and retains its old wooden panelling and atmosphere of edgy glamour. In 2002 it was actually the scene of a triad killing: a local property tycoon was shot in the head as he ate his breakfast. Here, in the mornings, you can still find waiters carrying snacks on trays slung around their necks, a style of service that predates the trolley.

A dim sum breakfast or lunch is a casual and often chaotic affair, but it has a few of its own, particular rituals. You may thank your host for pouring tea into your cup by tapping your index and middle fingers lightly on the table. This practice is said to date back to the late eighteenth century, when the Qianlong Emperor went on one of his fact-finding missions to the south of China. Travelling incognito, as emperors sometimes did in those days in an attempt to understand what was really going on in their realm, he dropped in on a teahouse with his small retinue. When the emperor poured them some tea, his footmen were flustered, because palace etiquette dictated that they should respond by falling to their knees, and yet they knew they should not give away his disguise. So they tapped their two fingers on the table as a miniature form of prostration, laying the foundations of a habit that remains common in Cantonese communities all over the world.

After my breakfast in Lin Heung, I wandered out into the streets of Central. In a market, an old woman was stripping the green peel from tangerines, releasing their sharp, citrus fragrance into the air. Nearby, the sweet, heavy scent of freshly baked custard tarts drifted out from a small bakery. Cured meats and sausages hung over market stalls; butchers worked with cleavers on wooden blocks. Behind every shopfront, red lamps glowed before shrines to protective deities. Hong Kong Island may have one of the world's most hypermodern skylines, and an infrastructure so efficient it makes you think cramming over a million people on to a tiny piece of land in the South China Sea is a great idea, but at street level, away from the designer shops and the grand hotels, you can still find the grit, the intense physical sensations, and the echoes of a much older China that give the city-territory its enduring appeal.

It was a soggy, sultry day. Rose had texted me the address of the restaurant. It was hard to find, hidden among the cafés and bars of the entertainment district. There was nothing around the nondescript entrance to suggest that this might be a place to eat: just a street number, and a dank concrete hallway leading inside. But the address seemed right, so I stepped inside, and took the small, dark lift to the fourth floor as instructed. There, I stumbled into a florist's workshop, where a Chinese woman was trimming leaves from the stems of roses. 'You here for the restaurant?' she asked. I nodded, and she pointed me towards an apartment door covered by a steel grill. A sign above bore the name of a company importing household goods. It didn't look promising, but the number was correct so I rang the bell.

A few seconds later, the inner door opened, and a man's face appeared behind the bars, looking blankly at me. 'Is this the right place for lunch?' I asked, doubtfully. He clicked open the grill for a second, and invited me in. The walls of the small, scruffy apartment were lined with cabinets filled with files and stacked boxes of napkins and tablecloths. More boxes were piled up on shelves near the ceiling, just as you'd expect from a company importing household goods. If it hadn't been for the tempting aromas and sizzly sounds coming from the tiny kitchen, and the three round tables set for lunch, I would have imagined I was in an office, not a restaurant.

Soon, Rose and her Cantonese girlfriends arrived, and we were all seated around a table in what appeared, from the built-in wardrobes, to have once been a bedroom. A few other guests arrived, and then the man who had let us in began to bring food out from the kitchen. There was braised duck with beancurd, an omelette with oysters, deep-fried prawns with white mugwort leaves, Chinese broccoli with dried fish, and a chicken soup with salted lemons. It was all rather delicious, and tasted even better because of the atmosphere of secrecy and adventure that surrounded our lunch.

The restaurant -- I wouldn't tell you its name, even if it had one -- was just one of the so-called 'private kitchens' (si fang cai) of Hong Kong. These illicit, small-scale eateries first sprang up in the wake of the Asian economic crisis of 1997. They were a way of making a little money without the interference of the taxman and government bureaucrats, and won their trade by word of mouth. Some were so popular that you had to wait months for a table.

Why would a sophisticated businesswoman like Rose want to dine in a cheap hole-in-the-wall restaurant like this? It's partly because of the thrill of the chase. Tracking down one of these rumoured establishments and bagging a table makes you feel ahead of the crowd. For the locals there's also, no doubt, a certain pleasure in cheating the government out of its taxes, and getting a slap-up meal at a knock-down price. Most of all, though, there's that slim but tantalising possibility of finding really marvellous and authentic Chinese regional food.

Since those early, heady days, the government has tried to rein them in, and many of the private kitchens have become legitimate restaurants. But if you know the right people, like Rose, you can still find the odd speakeasy, like the one we lunched at, which really is run illegally in the offices of an import company.

Hong Kong is a city obsessed with eating. Everywhere you go, there are people slurping noodles, devouring dumplings, picking up a skewer of deep-fried sparrows at a street stall. Sounds of frying and delicious smells emanate from all around. And if you start a conversation about food among Hong Kong Chinese friends, be warned that you will unleash a runaway train of food reminiscences, cooking tips, and hot restaurant recommendations.

And because the object of all this passion really is eating, rather than glamorous décor or being seen in the right places, people aren't snobbish at all. They know that you will very likely find the best beef noodles in Hong Kong at a shabby dai pai dong, or a sensational Muslim pastry in a shack in Kowloon. It's not uncommon to find rich men cracking open seriously expensive bottles of wine in some cramped backstreet café with chipped formica tables. And if you wander through the Wanchai wet market, you can be sure to see chauffeur-driven Mercedes parked nearby, their motors running as the tai tais (the Hong Kong equivalent of Ladies Who Lunch) buy impeccably fresh vegetables and seafood for their Thai or Filipina housekeepers to cook. So if word gets around that a good 'private kitchen' has opened, its phone will ring off the hook. Rose only got a table that day by the skin of her teeth.

On my last-but-one trip to Hong Kong, I was researching a newspaper article about restaurants and food shops. My editor had asked for 'the ultimate guide to eating in Hong Kong', and since I am very conscientious but had only five or six days at my disposal, I had to eat more-or-less non stop from morning till night. I would begin with dim sum, congee and/or noodles, then have a couple of lunches, spend the afternoon grazing in various food shops and cafés, and end the day with at least one dinner. I ranged widely in my explorations, from the grand Spring Moon restaurant at the Peninsula Hotel, with its fine teas and marvellous barbecued pigeons infused with osmanthus, to Mak's Noodles, where I lunched on prawn wontons in soup.

The private kitchens tend to have their charming eccentricities. One I visited was billing itself as Hong Kong's answer to El Bulli, and my evening there was a riot of fusion experiments such as 'steamed foie gras, sticky rice, and caramelised green daikon purée'. Another had a chef who worked during the day as a biochemical engineer; his hobby was cooking, so he spent his nights slaving over a hot stove, producing modernised Shanghainese delicacies such as a salad of beansprouts and fresh yellow lilies, and braised pork ribs with honey and vinegar. One of the earliest and most famous private kitchens, Da Ping Huo, was run by a Sichuanese artist and his wife who had shipments of chilli and Sichuan pepper delivered every week from Chengdu. She was a trained Sichuanese opera singer, so every night, after cooking dinner for twenty or so guests, she would come into the dining room and sing.

I ate many delicious things during that week, but the best meal of all was the last, a late-night supper in Cheung Fat, an old Chiuchow café in the district of Kowloon called Kowloon City. Chiuchow, or Chaozhou, is a region in the north-east of Guangdong Province with a distinctive cuisine that is little known outside Asia. In the nineties, when Hong Kong people had money to splash around, Chiuchow delicacies made with high-class (and high-price) ingredients like shark's fin or conch were all the rage. To me, however, the folk cooking of the region is far more inspiring. Chiuchow people specialise in cold cooked meats and seafoods, which are served with a dazzling array of dips and sauces. They are also known for their delectable stewed goose. They eat raw crabs and clams marinated in garlic, chilli and coriander; soupy rice with shellfish; delicate sweetmeats; and an addictive preserve made from Chinese olives and salted mustard greens. Chiuchow is one of my favourite Chinese regional cuisines.

Unfortunately I only realised that Cheung Fat was going to be the gastronomic highlight of my trip after I had entered the café, and by then I had already eaten one dinner at another Chiuchow restaurant on the Kowloon waterfront. At the first place, I had intended to order modestly, just for a taste, but the food was so good that I had ended up eating rather a lot of sweet-sour e-fu noodles, pigeon casserole, salted radish omelette and green beans with Chinese olive preserve. By the time I reached Cheung Fat, I was already full, and was planning on just having a quick sniff around before going back to my hotel to sleep. But when I saw the crabs hanging in the window and the extraordinarily delicious-looking fare on the tables all around, I realised that this would not be possible. So I tried to impress upon the waiter that neither I nor my Cantonese dining companion was actually hungry, while asking them to give us a kind of tasting menu of all their unmissable specialities.

Thus we ended up with another fourteen dishes for dinner. Of course they were all irresistible. Although Cheung Fat looks like a grotty little café, with its canteen-style furniture, humming fridges, scuffed vinyl floor and walls covered in pieces of paper scrawled with the names of dishes in Chinese characters, it is probably the best place in Hong Kong for grassroots Chiuchow cooking.

We munched our way through various cold, cooked fish dipped in Puning yellow-bean sauce; red-and-white crab with brown rice vinegar; aromatic cold meats that included the famous goose and also cuttlefish; large shrimpy creatures with plum jam; prawn cake with hair fungus and a treacly dip; deep-fried Puning beancurd; an amazing taro cake studded with pork and water chestnut; and a typically Chiuchow soup of bitter melon, soybeans, spare ribs and salted mustard greens. We ended the meal as we had begun it, by drinking tiny bowlfuls of roasted Iron Buddha tea. As you can imagine, by the time I arrived in Taipei the next day to begin intensive gastronomic research for another article, I felt ready to have a heart attack. But that's another story.

After that decadent dinner, I took a taxi back from the run-down ghetto of Kowloon City to the Peninsula Hotel, where I was staying in a four-roomed suite with picture windows overlooking the harbour, a private telescope and its own marble-clad jacuzzi. As always, Hong Kong seemed like a place of almost violent contrasts. There was my own personal seesaw between the pull of China and the longing for home, and between the conflicting desires of my Chinese and English selves; and then there were the contrasts of the place itself, between wealth and poverty, East and West, skyscrapers and street stalls, shrines to the ancient god of wealth and temples to modern mammon. Somehow, I reflected as I lay back in the froth of my jacuzzi, it had been a very typical Hong Kong day.