Ba Shan's snacky delights from the farthest reaches of the People's Republic could just be the best buns in Soho

It used to be so simple: do you want to sit upstairs or downstairs? Smoking or non-smoking? But at Soho's newly arrived Ba Shan, the dining choices go beyond the prosaic. Pi ying yuan, or da fu di?

Specialising in xiao chi, small, snacky dishes from the northern and western reaches of China, Ba Shan is the latest offering from the people behind the chilli-junkie's Sichuanese Bar Shu across the road, closed until June after a kitchen fire. It is immediately charming: a higgledy-piggledy collection of small, modest rooms, each representing a different part of a small Chinese town. Hence the necessary choice.

Tucked away behind the bar is a little "wine shop" dining-room, known as shou zong ge. At the back is the pi ying yuan, or "shadow puppet theatre", while downstairs is the farmer's cottage, bedecked with plastic vegetables. Upstairs is "the scholar's pavilion" and a private room called da fu di or "the grand official's residence". I'm just here for the tucker, not the poetry, so I take a small table with hard wooden stools in the first room on the ground floor, known as pin wei zhai, "the room for sampling flavours". Two walls of windows framing Soho by night alleviate any claustrophobia, as do the exquisitely decorated lanterns and bird cages, and an intriguingly different menu put together by chefs from Sichuan, Henan and Shaanxi, overseen by owner Shao Wei and the Chinese-food consultant Fuchsia Dunlop.

Guotie are always a must, and here the "pot-stickers" are unusually fine fingers of pastry wrapped around juicy chicken and shiitake mushroom fillings (£5.20), their little bottoms enticingly crisp and crusty. They do things the hard way here, making all the noodles, dumpling skins and sauces by hand, and basing soups on three subtly different base stocks.

But above all, Ba Shan has the best buns in Soho; soft little steamed lotus buns, green with spinach juice and stuffed with tender stewed pork (£2.80), and another, not dissimilar, jia mo steamed flatbread sandwich filled with feisty, succulent, cumin-spiced beef (£2.80). Be warned: steamed buns are about to take over the world; from David Chang's Momofuku Ssäm bar in New York, from Neil Perry's new Spice Temple in Sydney, and above all, from mainland China as it rises in power and culinary assertiveness. I could just eat lots of buns, have a beer and go home happy, but I drive myself on, through a delicate, fresh egg, chicken and laver seaweed "good luck" roll (£6) similar to Japanese tamago; punchy stir-fried water spinach jumping with Sichuan pepper and chilli (£5.50); and a deep bowl of Shaanxi noodle soup with pork, beancurd and "hot and fragrant" sizzling oil (£6.80), the noodles having a soft, wheaty resilience, the broth lightened with vinegar. Best is a crisp and crunchy cucumber salad (£4.50), which bends my head by contrasting the expected coolness of cucumber with the prickly, numbing heat of Sichuan peppercorns, like juniper berries with a licence to kill. All this works surprisingly well with a fleshy, fruity 2006 Antoine Chatelet Fleurie (£23.90) from the limited but serviceable wine list.

It's not quite the De Fa Chang dumpling restaurant in Xian, where I had a modest 17-course dumpling banquet, but it'll do. Dishes are small, and the prices soon add up, but it's worth it to have a meal of such distinct and interesting textures and flavours. Some dishes are bland, such as Beijing-style noodles with minced pork, or prawn-and-water chestnut dumplings, and even in the "hot" dishes, the spices and peppers are so well-fused, they are not coarsely up-front. So ask the extremely helpful, gung-ho staff for extra chilli oil if you need a hit, or just sit back and enjoy a gastronomic tour of the provinces of China that Chinatown forgot.

15/20

Scores: 1-9 stay home and cook, 10-11 needs help, 12 ok, 13 pleasant enough, 14 good, 15 very good, 16 capable of greatness, 17 special, can't wait to go back, 18 highly honourable 19 unique and memorable, 20 as good as it gets

Ba Shan, 24 Romilly Street, London W1, tel: 020 7287 3266. Open noon-11pm, Sun-Thurs; noon-11.30pm, Fri-Sat. Around £70 for two including wine and service.

Second helpings: Best of regional China

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