A Wong, 70 Wilton Road, London SW1 (020 7828 8931). Meal for two, including drinks and service: £80-£110

I believe I have found the single best dessert available right now in London, or, for that matter, anywhere else. It’s a wonder of patisserie that manages to combine the luscious with both precision and finesse. If I was told I could eat one last sweet thing before swearing off them for life, I would choose this, and then sit mourning the end of all that is lovely and true. Of course you want details but dessert comes at the end of the meal, and that’s where you’ll find the description. I had to wait for it and so should you.

I went to A Wong out of low-level guilt, an emotion I strive to avoid. After all, if I start feeling guilty, where do I stop? Nevertheless, I was a little sad about last week’s review: not so much about my assessment of Shuang Shuang – it really was exhausting – but that this should have been the last Chinese I reviewed before we celebrate the arrival of the New Year on 8 February. The year of the monkey deserves better, not least because Britain’s Chinese restaurants are in a good place right now. The over-sweetened knock-offs of Cantonese food, in sauces so orange as to make David Dickinson jealous, are in retreat.

A Wong is part of the good stuff. It opened in 2013 when Andrew Wong decided his LSE degree in anthropology was the perfect grounding with which to take over a generic Chinese in Victoria previously run by his father. That location, away from Chinatown, may explain the sense of liberation at play here. Regionalism, an understanding of China’s many culinary traditions, may be making headway in the UK, but Wong has a certain restlessness. He toured China, exploring its many cooking styles, before coming back to get to work. We are the beneficiaries of his travels.

I go at lunchtime, when the dim sum menu is the main show. It’s priced per single piece from £1.30 to £3 for the more complex items. Some of it sounds familiar, but there’s myriad diverting twists. The prawn cracker is identifiably so, but is a single large piece, the size of a plate, and used as a platform for a tangle of finely knotted deep-fried seaweed (or whichever brassica they’re using), a dollop of their own sweet chilli sauce, some pickled daikon, a smear of satay and a few other things besides.

A pork and prawn dumpling, as pert as an augmented breast but much more alluring, is topped by a curl of freshly fried pork crackling; a clear dumpling of shrimp wears a bonnet of a citrus foam, and while we are meant to point and laugh at such things, here it gives a bright acidic burst at just the right moment.

Then along comes a dish which impresses on simple craftsmanship. Shanghai soupy dumplings are clever, the filling of pork made with a stock which is jellied when cold but which, when heated, turns them into pouches of hot broth around the filling. Too often they stick to the greaseproof paper so that, as you lift them away, the shell tears, losing the prized soup. These hold together perfectly and deliver up a broth infused with handfuls of fresh ginger. It’s one of those items that makes you feel like a better person simply for having the smarts to eat it.

As does Chengdu street tofu, more of a hot set, savoury custard under a dressing of soy chilli, peanuts and preserved vegetable. Some dumplings are presented on small squares of AstroTurf, which is a little odd. Scallop puff three ways looks like a deep-fried sea anemone. It is a tangle of wispy, red, crisp tentacles and though I’m hard pushed to discern the three different ways or, for that matter, the scallop, it’s a pleasant textural experience. A mushroom, pork and truffle dumpling is a bun of earthiness and forest depths and winter darkness.

Then along comes a generous bowl of salt-and-pepper green beans, in a batter so lacy and transparent it could be on special offer at Agent Provocateur. I begin to think deep-fried things could be a lost health food. Everything has lightened again, not least because of the hefty slices of fresh red chilli. Inevitably, when so many items are at play, not everything can quite hit the mark. Barbecued candied pork jerky is a lot of great words pressed up against each other; in reality it’s just an overly lean square of tough, sweet bacon.

Their tea egg is a beautiful thing, with its gentle brown veining. It could be a prop in a horror sci-fi movie about alien spawn, just waiting to hatch. But it is another egg slow-cooked at 63C, with the unattractive jellied qualities those always bring, though the deep-fried shredded filo around it is a compulsive snack. It’s also interesting to discover that China, a famously lactose- intolerant country, has a cheese, from Yunan, served fried. It’s less interesting to discover it tastes exactly like halloumi.

But now we are at the sweet end of the meal, which naturally enough begins with pork, a sweet fragrant stew of the stuff, inside a sugar-crusted bun. It’s quite outrageous, and serves as a great support act to that final, perfect dessert: another bun, this time one as pale as a Jane Austen heroine, with a slight baby’s-bum cleft and a hint of rosiness so it resembles a white peach – a notion emphasised by a leafed twig. It contains a liquid centre of aromatic duck-egg custard: the silkiest custard, the most aromatic custard, simply the best sweet custard it will ever be your luck to try. The bun has a crisped base, which is a perfect textural counterpoint to the liquid centre. And now look: I’ve gone off on one. But it is a moment that simply stops all conversation and, with it, the meal.

A Wong manages the clever trick of being a relaxed space in which to eat serious food. There’s an open kitchen and a constant clatter, but at the heart of it are a bunch of dishes which punch above their weight at a good price. Granted we drank only water, but £70 for two was a steal for food of this quality. I’m late to review this restaurant, but can see why so many have already made such a fuss. I want to return to try the night-time dishes and the Peking duck tasting menu. And for the duck-egg custard bun of my sweaty palmed dreams.

Jay’s news bites

■ Sometimes a dish comes along that seems to have been created just for me. Yup, I’m that self-absorbed. So it is with the deep-fried pork ribs crusted with salt and chilli, in a huge pile of chillies and fried peas, served at Baiwei, a café on Little Newport Street in London’s Soho, and part of the Bar Shu Sichuan restaurant group. Those fabulous ribs cost £13.90 and are worth every penny.

■ A charity event run by chef Chris Galvin and maître d’ Fred Sirieix, Chocs 4 Chance, helps disadvantaged young people into work in the catering and hospitality business. Sixty food writers and chefs, including Michel Roux Jr and Marcus Wareing, have created unique boxes of chocolates to be auctioned for charity on Valentine’s Day (chocsforchance.org)

■ The Gallivant hotel in Camber, East Sussex has scrapped service charges, abolished the sharing out of tips among staff and given all employees a share of the profits and increased pay to at least the National Living Wage. Staff literally applauded the announcement (thegallivant.co.uk)

Email Jay at jay.rayner@observer.co.uk or follow him on Twitter@jayrayner1@jayrayner1