118 Strand Road, Portstewart, Northern Ireland (028 7083 1783). Meal for two, including drinks and service: £50

Last December, Harry’s Shack, at Portstewart on Northern Ireland’s north coast, issued a stark warning via Facebook. “It is simply not safe to come near us,” it said. “Do not even attempt it.” I can think of no other restaurant in the United Kingdom which would actively describe itself as mad, bad and dangerous to know; then again I can think of no other restaurant like Harry’s Shack. A ferocious winter storm, with winds fattened up across 1,000 miles or more of the North Atlantic, was bringing the sea up the beach, over the car park and to the very door. That day the restaurant didn’t just have a view; it risked becoming a part of it.

The day I arrive is more serene, but the waves are still huge – the furthest out to sea topped by a nimbus of spray – and the sound is a constant ear-filling bellow. I feel tiny there on the fragile shore, as if just footsteps from oblivion. Though the hour’s drive north of Belfast is a gentle affair, the destination is so dramatic you have to feel a little intrepid for having made it. With such a location a restaurant wouldn’t have to do much to be regarded as a gathering place. It could stay in business simply by not screwing up. Harry’s Shack – a long shed owned by the National Trust, occupying a low bluff at the edge of the dunes – does an awful lot more than not screw up.

It was opened a few months ago by Donal Doherty and chef Derek Creagh, the team behind Harry’s Restaurant just over the border in Bridgend where they have their own two-acre farm supplying much of the fruit and veg served here. Inside, the conversion has made it all raw wood and rough tables. There’s a wood-burning stove that scents the air, strings of fairground lights slung from the ceiling, and lots of big windows, because this is a view that must be present. You need to feel the uncompromising intensity of nature at your back: an intensity which turns you down towards the food on your plate. There are a lot of very good things to be looked at there, too.

I last came across Derek Creagh at a good gastropub in London, but I’d clocked him before. He was a part of the early brigade at Heston Blumenthal’s Fat Duck in Bray and, later, was the head chef at the Riverside Brasserie, Blumenthal’s first short-lived second restaurant, in a boat house by the banks of the Thames. At the Duck, Blumenthal spins fantasies from his ingredients. At the Riverside it was a steak with sauce Bordelaise and a perfect lemon tart. The food at Harry’s Shack most readily recalls the food I ate at the Riverside Brasserie more than a decade ago.

None of the dishes sound extraordinary. It’s straightforward stuff that doesn’t so much speak to an appetite nurtured by striding along the beach, as hector it. There’s a tottering burger, served with a steak knife through the top to keep the ingredients in place. There’s a brunch menu of pancakes with bacon and suchlike. And then the main plates arrive and you quickly realise that underpinning it all is serious knowledge. It is a menu of simple pleasures done about as well as they could be.

There are spiced whitebait, delivered in a cone of newspaper, with a saucer of their Marie Rose sauce. This is often one of those dishes that starts off irresistible and becomes increasingly less so, but these are pitch perfect – not breaded but dusted before frying, the sauce not tooth-achingly sweet but with just the right high-vinagered notes. I end up shaking the very last tiny fish out of the cone. There is an onion tart of bubbled, bronzed and friable puff pastry laid not just with a tangle of sweet, slow-cooked onions but with some that have been quickly pickled and still have their crunch. There are walnuts and leaves and a strident local cheese called Coolea, both as crumbly slices and whipped up to an absurdly rich dollop, like some grown-up, fancy-pants take on Dairylea.

Two hefty chicken legs from a bird that’s seen a bit of life, the skin roasted to a stickiness, arrive upon a heap of large macaroni with a light truffle cream sauce. It’s dotted with thick, porky lardons and slippery-sour pearl onions. A plate of the pasta alone would be a proper dinner. Throw in the chicken and you know it will see you up and down the beach again. Two thick fillets of expertly cooked gurnard are served on a bright mess of ratatouille, but it is the couscous side dish that’s diverting. It is lightly buttery and has toasted notes. More than that it has been spun through with blitzed preserved lemons. We spoon the couscous away neat.

And then dessert. There is a crème caramel with rhubarb and blood orange which is a reminder of why, done well, it is a beautiful thing. It has that soft, light texture that just makes you sigh. There is a chocolate pot. If it had simply been a glass jar of the milk chocolate ganache that would have been enough. It wasn’t. In the middle was a core of salted caramel. It was laid with lumps of chocolate brownie and a scoop of their own salted-caramel ice cream, and a big pillow of aerated cream on top of that. You want some right now, don’t you?

Though they are applying for a licence, Harry’s Shack is currently bring-your-own. If you want to drink you have to plan ahead or nip out in the car to nearby Divine Wines. This has the benefit of making it a cheap experience. Then again the prices are so stupidly low the bill’s never going to mount up. Those whitebait are £4.50, the tart a fiver; main courses are £12, the desserts £4. How do they make it stack up? By serving all day long. By having tumescent scones on the bar, and slabs of crisp-topped lemon drizzle cake. By doing everything so well that people drive from a long way away to get here. That makes total sense. I booked just before Christmas; in the first days of the New Year it received a bunch of awards. As a result it’s rammed. It’s as simple as this: coming to Northern Ireland right now and not going to Harry’s Shack would be a stupid thing to do. Just ask a local.

Jay’s news bites

■ The Riverside Restaurant in West Bay, Dorset, which reopens on 12 February, is protected from the worst the weather can throw at it by being situated just back from the sea. But the menu still shouts about its location. Go for fish soup or dressed crab, simply grilled fillets of brill or Dover sole or impressive seafood platters served both hot and cold. It’s been doing its thing since 1960, and keeps on doing it (thefishrestaurant-westbay.co.uk).

■ Genuine dismay among Francophile restaurant goers in London with the news that the highly regarded chef Henry Harris has sold his lovely bistro Racine on the Brompton Road. In a note to friends he blamed “a rapidly shifting residential demographic”. In short there are fewer neighbours to support a neighbourhood restaurant, as part-time residents buy up property. He is investigating re-launching a version of Racine elsewhere.

■ I’m not sure what this says about the kind of Christmas we had, but sales at pasty-pushers Greggs were up a whopping 8.2% over the holidays. Make mine a steak bake (greggs.co.uk).

Email Jay at jay.rayner@observer.co.uk. Follow Jay on Twitter@jayrayner1