The new 10th edition of the Harden's guide lists the best restaurants in London by category. The top Chinese for under £35 (a massive category encompassing every polished dim sum joint in Chinatown as well as the massed legions of China Gardens and Jade Palaces out in the suburbs) is a restaurant called Hunan on the Pimlico Road. This was startling news. The Pimlico Road is generally known for the grossly over-priced antiques shops flogging pointlessly gilded nick-nacks to the inbred, snorting Chelsea girls with too much money and not enough taste who live nearby. It is where you go for an emergency rococo mirror. It is not where you go for great Chinese food.

Except, of course, that according to the punters who contribute to Harden's, it is. And they are right, though God knows how they found it in the first place. Hunan is not a glossy establishment and you could quite easily miss it. Which I and my companion Robert almost did.

Once, Robert was a banker, but, as he puts it, greed forced a career change upon him - during incessant business lunches he began to find the food more interesting than the business under discussion. And so he became a restaurateur instead. Certainly he is a man who knows his Chinese food. He even claims to possess a recipe for bear's paw 'in the Hunanese style'. 'Though it says you can substitute beef for bear' - helpful given that Robert lives in east London, which is a bit light on wild bears these days.

There may or may not be bear's paw on the menu at Hunan. To be honest, we gave it very little attention save to note that, for a Chinese restaurant, it is exceptionally short. We had been advised, both by Harden's and the waiters, to place ourselves in the hands of the owner, Mr Pang. He would see us right, we were told. And he did.

Mr Pang is probably the only acquired taste at Hunan. He tends to hover a little, looking for your approval and grinning like an indulgent nanny as each dish arrives. But then, when the food is this good, who can blame him? We gave him few directions, save that we didn't mind a bit of chilli - useful as its a key flavour in Hunanese food - and that a bit of seafood wouldn't go amiss. Mr Pang grinned some more.

We began with little bamboo mugs of a steaming, aromatic broth heavy with pigeon breast that had been steamed and then minced. (We know this because we asked; a friend of mine, who is a non-meat eater and a regular at Hunan, only discovered that he has been eating pigeon for years when he and I compared notes.) Next came minced chicken in a sweet chilli sauce to be wrapped in crisp lettuce leaf. That was followed by the best, sweetest prawn toast I have ever tasted.

It should be said that none of these dishes were huge; each was little more than a forkful, so that there was space for the next. When we asked for a bowl of rice with which to soak up the sauces, Mr Pang almost refused. 'It will fill you up,' he said with disdain. He didn't want that. The kitchen was only just getting into it's stride.

There were green beans in a light batter with chilli and salt. Four gorgeous dinky mushrooms came stuffed with minced pork and topped with a sesame crust. There were slices of pork fillet in a sweet unctuous sauce that remained crisp despite being served en papillote. Then came two perfectly formed dumplings stuffed with spinach, water chestnut and sweet basil. We know this because Mr Pang insisted that we identify them. Robert got them all; I trailed in behind with just the spinach.

The next dish, shredded duck with plum sauce and pancakes, was the only slightly duff note. The perfectly rendered crispy dusk had been swamped in a sweet chilli sauce. No matter. As a palate cleanser there was a dish of fresh spring vegetables and one of chicken, stir fried in a very different and chilli sauce. (A warning: don't go to Hunan if you're not keen on chillies; it would be like someone with a fear of heights going up the Eiffel Tower.)

For pudding we shared a light and delightfully bland almond jelly - exactly what was needed after such a massive assault of flavour. There is no doubt that, with Mr Pang's help, we pushed the boat out and the bill for £72, which included service and a few beers, reflects that. But give Mr Pang a budget and I'm sure he'd keep to it. Just don't ask him for the menu. Mr Pang does not hold with menus.

Hunan, 51 Pimlico Road, London SW1 (020 7730 5712). Dinner for two, including wine and service, £70. Harden's guide to the best restaurants in your area will be free exclusively with The Observer on 12 November. Contact Jay Rayner at jayrayner@observer.co.uk