There are not, as far as I know, any abattoirs in Britain with cafes attached. I doubt this is a business opportunity missed. For all our growing insistence on knowing the origins of the ingredients served to us, there is still something about the buzz of the stun gun, the squeal of the piggy and the whump of the carcass as it hits the slaughterhouse floor which could only ever contrive to dent the appetite. We do not feel the same way about seafood. The closer to the sea, to the nets, to the bubbling oyster tanks, the better. We want to eat our fish in pared-down conditions; I swear that if somebody set up a cafe aboard a trawler which steamed out to sea for every service, it would do a roaring trade. This is probably because nobody, other than a very lonely, rather twisted deep-sea fisherman, has ever developed an emotional attachment to a red mullet. Put it this way: have you ever heard a little red mullet whimper in pain? No, neither have I. We are happy to eat our fish at source.

Or at the very least, I am, which is one of the reasons I was so taken by the Abbotsbury Oyster Farm and Seafood Bar, near Weymouth in Dorset. It occupies a ragged boatyard of a site overlooking the eastern end of the Fleet lagoon, just before the bridge to Portland Bill. The Oyster Farm is not a pretty place, but it is lousy with authenticity. The 'restaurant' itself is little more than a shack, at one end of which is a door through to the purification tanks, holding stocks of live oysters, scallops and mussels which are for sale. Inside there are just a couple of bare wooden tables, forcing most people to sit at picnic tables outside in the gravelled yard (although there are plans to build a larger conservatory). It feels right, or echt, as Mittel Europeans might say if ever they had good reason to visit Weymouth.

The menu is short, and shorter on some days than others. All the fresh fish - on the day we went, the menu listed grilled skate, brill and plaice - is provided by a local fisherman who runs a day boat straight off the jetty. If the weather is bad and he can't get out, there's no fish. Simple as that. The weather was good the day my family visited, but it was of no import; for the most part we stuck with the shellfish.

I ordered the Portland crab. It was a huge beast for £10 which turned up partially cracked, on a big shiny tray accompanied by nothing more than the tools with which to get at the meat. Chunks of nutty brown bread, dishes of luscious mayonnaise and a bowl of those perfect golden chips that rustle against each other when they are moved - all extra - completed the meal, and it was more than enough. The crab was the way you always hope it will be: sweet and salty, with that aromatic edge of the sea. My wife went for one of the more complex dishes - six chunky king prawns in garlic butter thick with sweet tarragon. And for our three-year-old, a bowl of slightly undersalted whitebait which was swiftly emptied. Delicious all. We did not order wine, but there is a short list, mostly of New World whites, all at less than £20 a bottle.

If ever I go back - and I hope to - I would want to try the oysters, served straight up at £8 the dozen, grilled with herb butter or cheese or flash fried in wine; I would need to find co-conspirators to help me demolish the crab and shellfish feast, £28 worth of whole crab with hot shellfish and a spicy lemon sauce designed for three to four people; I would want to have a go at the seafood platters and the moules and the doorstep-thick crab sandwiches. And I would feel clever simply for being there amid the utilitarian landscape of fishing skiffs and filtration tanks and coiled ropes, listening to the lap of the water and smelling lunch on the salty air and knowing that this is exactly how a fish restaurant should be.