Radici, 30 Almeida Street, London N1 1AD (020 7354 4777). Meal for two, including drinks and service: £40 to £120

There is one dish on the menu at Radici, a new Italian in London’s Islington, which sums up the restaurant. It is listed under “Primi” as “taglierini, fagioli and pancetta”. That’s ribbons of a thin tagliatelle-style pasta, white beans and bacon, in a dense, starchy broth of such intensity and such conviction, you could be forgiven for thinking your very soul is lost somewhere in its depths, undergoing respite care. It is the domestic eaten outside the home; a bowlful of muchness, built on very little. It costs £8.

That number is the remarkable bit, because the chef here is Francesco Mazzei. Over the years, I have associated Mazzei with many things: precision, class, an understanding of comfort. I’ve never let the word “value” get anywhere near his name and that £8 price tag really is value. Frankly, I didn’t even know he could do single digits. I’d go further. Over the years, I’ve actively overlooked the large matter of price because of the profound joys of his cooking, which is always right and always encouraging.

At L’Anima in the City, the restaurant was all snowfields of linen and huge glass windows. It was sunlight, the gentle pad of well-shod waiters’ feet, and a clientele that looked fluent in the language of high net worth and tax dodge. I always made a point of looking instead only at my own companions, and revelling in Mazzei’s seafood fregola, a stew of toasted grain in a crustacean-heavy broth of glorious poise and briny power.

Last year, he gave up on L’Anima and moved his shtick to Sartoria in Mayfair, where the cushions are softer, the floors carpeted and most of the glowing perma-tanned punters look like the clients of the big city boys who frequented L’Anima. His fregola is still on the menu and it is still brilliant. It is also still £24.50. He prepares truffled pastas, and a zabaglione like some boozy cloud, to be spooned from a big, shiny copper pot. I would take seconds and perhaps thirds, and mutter to myself that food of this quality was wasted on all these people who just happened to be able to afford it.

Radici – it means root – is the solution to my reverse snobbery. Like Sartoria it is owned by D&D London, the successor company to Conran Restaurants. For many years the broad, low-slung space was home to Almeida. It took its name from the street address – it’s just opposite the Almeida Theatre – and served a take on French bourgeois classics to an Islington set that thought it knew about these things. They did a good line in terrines and rillettes. So pig parts and pig fat, basically. Nothing wrong with that, but it remained, to be blunt and only mildly cruel, one of London’s also rans. I never met anyone who ever ate there.

Now it has been renovated. The gastronomic centre of gravity has shifted from the Dordogne to Puglia and all points south. The walls have been lightly distressed in the right shade of beige and a large wood-fired oven installed. It is rustic for city people like me who don’t do countryside. This could be dismissed as Mazzei’s diffusion line; I prefer to think of it as the point of having him. Because the menu he has written is as flexible as an Olympic gymnast. You could come here for a pricey starter of roast octopus, the white and purple tentacle curling prettily on the plate, with nutty cannellini beans and crumbles of a smoked cheese under wilted leaves. You could follow that with roasted king prawns for just shy of £20, and send it all on its way with a bottle of something hefty and bruising from Sicily. You would run up a sizable, London-style bill of the sort that makes lots of people cross.

Or you could come for an £8 bowl of that soothing pasta, or for a sourdough pizza, with a rim of blistered edges at a price to rival the cookie-cutter high street. Throw in a glass of good red and get out for under £20 a head having been well fed. Up to now Mazzei’s restaurants have told you how to use them. Come here for a big dinner. Leave poorer. Radici says: “Do with me as you will.”

Among the snacks for £5.50 is a plate of peas in their pods, that have been slicked in oil and salt and griddled. You drag them through your teeth, the pods gusting hot perfumed air into your mouth, before releasing the crisp, youthful peas. It is a compelling and meditative process and, presumably, will be gone from the menu soon, as the season passes. A plate of salami and cheese is generous and served, rightly, just on room temperature. I can’t pretend a machine-cut Italian ham will ever challenge a hand-sliced Spanish, but then it’s half the price.

There’s that list of pastas – a seafood fettuccine here, tiny ear-like shells filled with ricotta and fresh herbs there – and then the pizzas. My calabrese is layered with thick, fatty salami that has run in the heat, dollops of pesto and small piles of seriously powerful ’nduja, the chilli-boosted soft salami that in the oven has become a crisped heap of salt and fire and meatiness. It is a lot of pizza for £12. The margherita is £8.

Of the pricier mains, try the calf’s liver, rolled up on itself, wrapped in pancetta and then wood-oven roasted. It is served with a still smoking rosemary twig as a tail, to remind you that real flames have been involved. There is, of course, a pillow of unfussy mashed potato. If you do not order Mazzei’s zucchini fritti, exploding from their pot like some desert grass that’s bolted, you are an idiot. They are the thinnest and the crispiest in London. If you attempt to eat these with cutlery, you are either strange or so uptight, you probably carry with you an anti-bacterial hand gel for when you touch your own children.

I complained recently that not enough restaurants have serious dessert menus. Radici has one. There is an almond cake with mixed berries, a marsala tiramisu with a radical crunchy base and best of all, a proper syrup-drenched rum baba flavoured with bergamot. Whorls of cream, topped with crumbled pistachios, soothe the sweetness. I spoon it away and like all the plates here, it goes back empty. You could keep the bill down by going without. But really: why would you not want to mislay £7 on that?

Jay’s news bites

■ For more wood-fired oven fun, there’s the small chain 500 Degrees, with outposts in Brixton, Croydon, Crystal Palace, Herne Hill and Dagenham. As per the temperature in the name, all pizzas boast a proper charred crust. Pricing is keen, with pizzas starting at £4.95 for a simple marinara and going all the way to £8.95 for the capricciosa, with ham, artichokes and mushrooms (500degrees.co).

■ Santo Remedio, the Mexican restaurant reviewed so admiringly here, and which had to close due to premises problems, has a new London site. Soon we can eat their tacos of braised beef with salsa roja again. All they need is £40,000 in crowdfunding to get the place up and running. Visit kickstarter.com and search for Santo Remedio.

■ Danny Gill, formerly the head chef of Daniel Clifford’s much garlanded restaurant Midsummer House in Cambridge, has bought his parents’ pie restaurant Browns in Lincoln. They sell pies to take away alongside an eat-in menu (brownspieshop.co.uk).

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