In Thailand’s capital, a culinary tour forgoes restaurants in favour of hot and fragrant street food.

Bangkok is a shimmering sprawl of concrete, punctuated here and there with the glitter of jewelled temples; it makes you catch your breath in wonderment. It’s also teeming with places to eat, from the restaurants in the ultra-luxury hotels – our room in the world-famous Mandarin Oriental (mandarinoriental.com) has a button by the bed that says, simply, ‘butler’ – to the millions of street stalls that collect on every corner like bees on honeycomb.

But we're lost. Research delivers torrents of conflicting opinion and concierges want to send us to farang(westerner)-friendly, air-conditioned joints where few Thais ever venture. So we join the rich in beautiful dining rooms, like The Peninsula's Mei Jiang (peninsula.com) where we eat exquisite dim sum - rolled noodles with black beans and chilli, snow pea pastries, roast pork puffs so buttery they're like pig shortcakes - and are treated like pashas.

We sip cocktails on the Mandarin's terrace, watching the long boats buzz down the Chao Phraya river; we try to get staff at swanky (and excellent) Celadon at The Sukhothai (sukhothai.com) not to give us toned-down, foreigner-friendly spicing. This sends them into a tailspin, and results in a kaeng phèt pèt yang, red duck curry, that's almost lipstick scarlet with chilli. It's a carnival in the mouth. The staff hover round us in mild panic; I think they're expecting us to combust.

And we hit the notorious bars in the sky: Vertigo, atop the Banyan Tree (banyantree.com), which has D gibbering with health-and-safety-induced anxiety and requires us to neck two vast martinis each to facilitate the walk down the vertiginous steps clinging to the side of the building. And Lebua's Skybar (lebua.com), which appears to jut right out into the night. We wander round extraordinary shopping malls with their chichi tearooms, designer sushi and foodhalls offering the solution to all your Epoisses and Nutella needs. It's a gas, but not helping us get any sense of reality.

Then salvation arrives in the form of Bangkok-based chef David Thompson, Michelin-starred for his Thai restaurant nahm in London's Halkin hotel (halkin. como.bz). Not only is he happy to meet up, he wants to show us round. This is a bit like winning the lottery. Twice.

David is not averse to the high-end stuff, but he tells us that Thais don't have a restaurant culture as such - it's all about market food - and he's going to help us scratch the surface.

First stop is the roiling insanity of Chinatown - much of Bangkok's street food has Chinese roots. Nai Mong Hoi Thod (539 Thanon Plaeang Nahm) sells nothing but oyster omelettes, crisp from tapioca flour and long-frying on an ancient, seasoned wok in rendered pork fat. Fat glossy oysters sit on top, ready to be seasoned with sriracha (bottled chilli sauce) and lashings of white pepper. A couple of doors down, we stop for implausibly good, toffee-coloured, sugar-cane-smoked duck and a bottle of Mekhong whiskey, the kind of firewater that means you wake the next morning still plastered.

Then to Yaowarat, Chinatown's main drag, for creamy lobes of durian, like a mash-up between foie gras, blue cheese and vanilla custard with maybe a touch of unwashed foot; worryingly, David tells us that eating durian after drinking hard liquor can cause you to explode. Oops.

Sadly, David has to leave us to attend to his lovely new Bangkok restaurant, nahm (metropolitan.bangkok.como.bz). Panic? Not us. We're emboldened now, enough to go down a dirt track, past wooden shacks where people live their whole lives in one tiny room and up rickety wooden stairs to Kaloang Home Kitchen (2 Sriayudhaya Rd, Sisaotaves Dusit 00 662 281 9228), where ants crawl over the dilapidated tables, there's a gentle breeze from the river and a superannuated ladyboy (ladybloke?) entirely ignores me while plying with surprisingly excellent food: smoky, chargrilled seabass and giant prawns with viciously hot nam phrik dip.

Then there's the defiantly ugly My Choice (Sukhumvit Soi 36, 00 662 258 6174); the Thai love for OTT decoration hasn't touched this place. But the banana blossom salad more than makes up for any decorating shortfalls, that and its legendary roast duck. There are forests of alien vegetables: tua phu, meaty winged bean; loofah-like buap liam; sa taw, curious-smelling twisted cluster beans. We don't quite get round to fried fish intestines or pond snail curry.

We find humble shophouses like Roti Mataba (136 Phra Athit Rd; 00 662 282 2119); fwap, fwap, fwap goes the lady at the grill, slapping the dough into the most unutterably delicious, flaky rotis to be stuffed with curries or slathered with condensed milk. Or renowned Thip Samai (313 Thanon Mahachai, near the wonderful Phratu Phi street food district), a vision of inferno, open burners showering the pavement with sparks. It's rammed with people scarfing pad Thai of such fresh, vivid, luxurious flavour that it makes any you've ever tried before taste almost laughable.

And there's Bo.Lan (bolan.co.th) opened by a pair of young ex-nahm chefs, a groundbreaking and beautiful place where they recreate ancient and authentic Thai recipes: they aim to be 'as Thai as we can', so no concessions to nelly Western tastes. Wow, oh wow - our heads are blown off by pheasant with green peppercorns, river fish in banana leaf with red curry and some remarkable relishes: rose apple with cashew, cured pork with coconut cream. Pork floss? Where have you been all my life? The flavours are so intense, we feel almost trippy.

Sure, we have the occasional strikeout, like when I try to track down Lao/Isaan cuisine, featuring the likes of grilled chicken, sticky rice, som tum green papaya salad and red-ant-egg dip (well, maybe not so much that last one). We wind up in Balee Laos (86/8 Soi Sukhumvit 16; 00 662 663 1051), a jungly shack where fat, middle-aged farang paw long-suffering Northern Thai girlfriends and I become entirely invisible. We don't have a great deal of luck with street food - especially a positively alarming experience we have in sleazy Patpong where the chicken looks suspiciously like rat (another Isaan specialty; no, really).

But Aw Taw Kaw market (or OrTorKor, Phaholyothin Rd) opposite the Camden Markets-on-steroids Chatuchak is a jewel. OK, it may be a little sanitised, but it's the Bangkok equivalent of Borough or Barcelona's Boqueria, where well-heeled locals shop for the finest produce. You'll find rows of ponging durians and fragrant mangoes, the freshest fish and seafood, sauces, relishes and dressings - but the restaurant stalls at the far end of the market are genuinely sensational. Fermented sausage (sai grok) that explodes on the tongue into a kaleidoscope of dancing flavours; a rainbow of curries; incendiary chilli-laced salads (larbs); soups, noodles and roasted meats; intricate, paintbox-coloured sweets. Since we've been home, my tastebuds miss this place every day. Everything here seems so... flat by comparison.

Am I now an expert on the Big Mango? Not likely. But I do realise that most of what we happily wolf down over here isn't fit to touch the hem of the humblest shophouse in the Thai capital. We simply can't replicate the almost outrageous flavours. In this steamy, frantic, uglybeautiful, often malodorous megalopolis, the people know how to live. And, woah mama, do they know how to eat.

About the author
Marina O'Loughlin, London newspaper Metro's restaurant critic, has remained incognito for the past 11 years. She regularly travels the UK and abroad in search of culinary adventure.