'We eat too much, if only to confirm they can keep up the standard. They can'

Restaurants can be like clever comedy: it's the seemingly throwaway lines that are the most telling. Our meal at The Dairy is bracketed by a duo of remarkable acts, neither of them ordered or charged for. As curtain-raiser, homemade rustic bread in a jute sack, served with a dollop of room-temperature butter smeared, as is the fashion, on a large pebble. It's a curious, not entirely appealing colour. But wow, the taste: it has been whipped up with smoked bone marrow. I didn't think there could be anything more luscious than good butter, but it seems there is.

And then the finale, just as we're winding down. A vintage biscuit tin with a scrumpled menu inside. On it are weeny homemade doughnuts, still warm, dusted with something peppery and aromatic (hibiscus sugar? Er, pepper sugar?); shards of the thinnest, most friable shortbread; and limpid apple jellies, concentrated appleyness, as sour-sweet as a gourmet Tangfastic. These may not have starring roles on the menu, but they're scene-stealers, little extra nuggets of solid gold after the credits have rolled.

If this is the stuff they give away… well, it's clear we're somewhere a bit special. The Dairy opened a few months ago with no marketing or publicity, but a ready-made audience of well-off restaurant-going neighbours pining for something better than Clapham's leerier joints. (It was food writer Diana Henry who pointed me to it.) The brick, neon and "reclaimed" furniture looked more nouveau burger bar than gastronomic blast, but slowly the jungle drums started pounding and the place has been rammed almost since day one.

No wonder. Our meal is a series of small thrills. From the little explosions of taste in a pea dish – thyme buds, lemon verbena jelly, mint granita – to the almond milk that comes with small rectangles of pork belly, it makes you beam with pleasure at the knowledge there's more to come. Chef Robin Gill's CV reads like a box-ticking of places to namedrop, including Noma and Le Manoir aux Quat'Saisons. Their influences are plainly decipherable: the herbs and vegetables grown on the roof (sorrel and mint, broad beans and radishes); their own beehives; an emphasis on seasonality and the cult of the ingredient.

Take those peas: cooked just enough that there's still bite, with weeny cubes of blanched celery, fronds of celery leaf, torn nasturtium leaves and a mound of mousse so light it looks set to float off the plate. It has a wreathed-in-sunshine brightness of flavours. The pork belly's skin is so thin and crisp, its flesh and fat so marshmallowy, it's like eating piggy crème brûlée.

We eat too much: chicken liver mousse of preternatural lightness with a cap of peach and apple; a scotch egg where the sausagemeat is made from squid and a loose, pungent chorizo, the quail's egg yolk still almost liquid. But it's hard not to – if only to confirm that they can keep it up. They can.

There's an endearing knockabout quality to The Dairy: the fact that it operates as a cocktail bar till the wee small hours; the informality of both setup and staff; those old-school chairs and cinema seating, which I suspect aren't really salvaged at all. Some of the dishes could be finessed (I'm thinking of a slab of slow-cooked short rib that had a slight whiff of school dinner about it). And I do worry about the staff, tottering under the weight of heavy stoneware, bowls and basins, seemingly designed for Game Of Thrones feasting, not Clapham noshing. But I'd far rather be eating Robin Gill's wonderful food here, with his wife Sarah in her slouchy shorts singing the praises of their quirky and alluring wine list (we love the dangerously gluggable, unfiltered, natural Litrozzo from Lazio) than in some constipated temple of haute cuisine. Lucky Claphamites: with the arrival of this star turn, they're laughing.

• The Dairy 15 The Pavement, London SW4, 020-7622 4165. Open Tue 6-11pm, Wed-Thu noon-11pm, Fri noon-midnight, Sat 10am-midnight, Sun noon-8pm. Dinner £20-25 a head, plus drinks and service.

Food 8

Atmosphere 7

Value for money 8

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