Lucas Hollweg reviews RockFish Grill & Seafood Market

My parents came up to meet me for lunch. They live an hour and a half away, where the hills roll up towards Exmoor and the West Country gets wild and woolly. There was a time when they would go to Bristol regularly, but neither has been much recently. "It used to be so much easier to get here when you didn't have to obey the speed limit," my mum said when I met them at the station. I took them to the RockFish Grill & Seafood Market in Clifton, a neighbourhood that perches like a Georgian wig above the city's warehouses and docks. The restaurant is owned by Mitch Tonks, the fishmonger, self-taught chef and television personality, who seems to be taking over from Rick Stein as Britain's fishy champion in chief. Most critics have said good things about his other restaurant, The ­Seahorse, in Dartmouth, but nobody seems to have written about this one, which opened this summer, perhaps preferring the prospect of a jolly jaunt to the seaside.

The Bristol restaurant fills a site formerly occupied by a branch of FishWorks, the chain Tonks founded nearly 15 years ago. FishWorks was a singularly good idea: a shop selling sparklingly fresh fish attached to a democratically priced brasserie. It filled a happy middle ground between "fine dining" and the salt and battery of the British chippy. But the company got into difficulties when it went public a few years back, opening too many branches too quickly, and Tonks left, unhappy with the compromises involved. I'm glad he stuck to his guns. RockFish has taken things up a rung or two, but its heart is clearly still in the same place. It's a bright, convivial and instantly likeable room, with bookcase shelves filled with wine, pictures of fish on the walls, button-back leather banquettes and a view of the open kitchen in the corner. It was filled on our visit with the quiet rumble of contented diners - most, it has to be said, of a similar age to my parents, though maybe that's just who eats fish on weekday lunch times in Bristol. I imagine there's a more mixed crowd in the evenings.

The back room houses the fish market, a dripping, ice-strewn counter glistening with a small but select gathering of home-grown piscine talent. The catch is brought fresh each day from the market at Brixham in south Devon. Tonks divides his time between the two restaurants and, the day we went, was in the Bristol kitchen, sporting his whites and rather a natty pair of spectacles. When I went to look at the fish, he came out to talk me through it, telling me how good the red mullet was right now, pointing out the Lyme Bay scallops and extolling the virtues of Brixham's rope-grown mussels. He clearly cares about what he does.

The menu at RockFish works on the sound principle of taking something good and doing as little to it as possible. There are oysters and mussels and shrimps on toast, platters of fruits de mer, grilled monkfish, roast sea bass, seafood stew, fritto misto - and a decent hors d'oeuvre bowl of smoked cod roe, which we dipped into while we thought about what to eat.

My parents were overcome with chronic menu indecision, so I ordered for all of us. We started with a bowl of Brixham mussels, a Dartmouth crab salad and some scallops, which we passed around between us. The mussels, steamed with chilli, bay and garlic, were plump to the point of obesity, their cooking juices lifted by a hint of fragrant heat. The crab, which came with mayonnaise and the simplest of fennel and gem salads, was rich and sweet, and the scallops, roasted in their shells with tarragon, white port and garlic butter, a gluttonous pleasure of silken nuggets in a lickably good sauce.

As we ate, we talked of family and friends and fishermen. The conger eel competition we once watched on a damp day by the Bristol Channel, when a 6ft monster won its beaming captor a portable telly. The friend who would stand for hours at the edge of the sea, casting into the waves in the hope of landing a sea bass, though he never did. And the last remaining mud-flat fisherman in Bridgwater Bay, who slides out on a sledge between tides to harvest the fish from his nets.

Main courses were a whole roast john dory, some rosemary-stuffed red mullet and a "skate" wing, which was actually from one of its more sustainable cousins, the starry ray. Skate is one of those fish that is off the menu these days, but most people wouldn't know a ray if it zapped them (or indeed, which of the many species of ray it's acceptable to eat), so the skate label has stuck. Everything was perfectly cooked. The ray wing, crusted gold from its pan, separated into soft sheets when prodded with a knife. The mullet came burnished from the heat, a pair of rosy and rich-fleshed Piscean twins, while the john dory was firm and delicate, with unusually chunky fillets beneath the crisp skin. It was all adorned with nothing more than half a lemon, with, on the side, a caper sauce to go with the ray, a bottle of olive oil and some bowls of tartare sauce and parsley and garlic dressing, to be splashed and dolloped at will. We also had some chips, a fennel gratin and a pert little salad of dressed leaves and radishes.

We finished it off with a shared bowl of sunset-red poached quinces, some fat prunes and a jug of frothily light vanilla-freckled custard. It was a simple and delicious autumn pud. The service was smiley, knowledgeable and interested. Tonks himself came out of the kitchen at intervals to ask how everything was and chat with what were evidently regular customers. With a bottle of Tonnix, a Portuguese white blended by Tonks and his mate Mark Hix to go with seafood (Ton-Ix, geddit?) and three espressos, the bill came to £118. That isn't a lot to ask for a good lunch, and you can get two- and three-course menus for £15 and £20 a head.

This isn't posh food. There are no foams or decorative smears or pluches of micro leaves, and if that kind of kitchen cleverness is what floats your boat, then RockFish may not. But it filled me and my parents with a warm glow of happiness. If you're going to do food this simple, it needs to be impeccably good. There's nowhere to hide. Fortunately, Tonks and his team don't have to.