JOHNNY'S HALF SHELL -- 2002 P ST. NW. 202-296-2021. Open: for lunch Monday through Saturday 11:30 a.m. to 3 p.m.; for dinner Monday through Thursday 5 to 10:30 p.m., Friday and Saturday 5 to 11:30 p.m.; light fare Monday through Saturday 3 to 5 p.m. Closed Sunday. AE, MC, V. No reservations. No smoking. Prices: appetizers $3.50 to $9.50; lunch entrees $5.95 to $18.95; dinner entrees $11.95 to $18.95. Full dinner with wine, tax and tip $30 to $60 per person.

The recipe for classic Maryland crab cakes doesn't stop at the stove. The way they're served counts, from the plate (thick and chalk-white) to the table covering (if you've got to have cloths, cover them with glass) to the flooring (tiny tiles). The crab cake of our dreams is served by somebody matter-of-fact yet friendly, who's not wearing a jacket unless it's a white uniform. Working back from there, a great crab cake is plain -- a little mayonnaise, a touch of salt and pepper, and maybe mustard, cayenne, Old Bay -- but not boring; it's barely more than fat, snowy lumps of backfin meat so fresh it's nearly sweet, so moist it almost holds together by itself. A great crab cake might be broiled or fried, then it's served naked except for tartar sauce so tart, crunchy and sprightly that its remains demand to be slathered on crackers or bread.

Johnny's Half Shell has the recipe right, even to the slight inconsistencies from day to day that reassure you it's always freshly made.

This new seafood restaurant also has the right recipe for great grilled squid, fried oysters and even spicy wood-grilled chicken wings that could wipe Buffalo right off the map. It sautes soft-shell crabs like a Chesapeake waterman, and it understands that crab imperial is a peasant-plain dish: a lot of crab and a little cream with a few bread crumbs to protect it under the fire.

I'm not suggesting that Johnny's is a perfect seafood house. (Sometimes that crab imperial needs a sprinkle of salt to wake it up.) But who could expect perfection in a mere matter of months?

It's the work of Ann Cashion and her partner, John Fulchino, so you expect a certain basic quality. And the space it took over from the defunct Blue Plate is cozy and homey, with tables in front, booths and counter seating in back. The improvements in lighting, paint, woodwork and the like have subtly made it feel more rooted and neighborly. It comfortably lives up to its down-home name.

I've been to Johnny's a lot. Once you've discovered it, it's hard to stay away. By now I've tried it all and homed in on my favorite dishes. The menu isn't long -- about a dozen appetizers and soups, a few salads and eight entrees -- but I'm tempted to stick to the appetizers time after time. My meal of choice would start with oysters -- two kinds -- and clams on the half shell, available by the piece. Of course I'd team them with a white wine from the small but well-chosen list, one day trying an Australian chardonnay, another day one from South Africa, or a muscadet, all in the $20 to $30 range.

I'd never pass up the grilled squid, its curls and tentacles crisped on a wood fire and drenched with lemon, with crunchy strands of fried shallots and a mound of tender young spinach. Barbecued shrimp are some of the sweetest, juiciest shrimp in the city, rubbed with hot spices and sometimes too much salt, but tamed by chewy, coarse and creamy grits with Asiago cheese. And the cornmeal-fried oysters crackle their way into your affections. The oysters themselves aren't as flavorful as those on the half shell, but the dish is nevertheless glorious, with a fluff of gently pickled vegetables.

If I had to find more to order, I'd just call for the rest of the appetizers: the half-dozen littleneck clams roasted with julienned zucchini and garlic in a light, fragrant broth; the intense, unthickened gumbo packed with shrimp, oysters, fish and sometimes lobster; the Manhattan clam chowder so fresh and delicate it could convert us New England patriots; and the vegetable salads. Cashion serves one of those perfect green salads, with just enough mustard-sharpened dressing clinging to fragile mixed lettuces. The fettuccine is also pleasant, a quiet tangle of noodles with mussels enveloped in a wisp of buttery cream. The gravlax is fine, though no competition for the other seafood.

Most people, of course, order entrees, especially when there are such options as seafood stew, fritto misto and wood-grilled lobster. These all fall short of my hopes, though. The stew is made from ingredients of impeccable quality but it has a tearoomy sweetness. Fritto misto also seems flat, its perfectly crisp batter unseasoned; a pile of excellent seafood has been rendered bland. And grilling lobster turns it chewy, while a heavy dousing with Old Bay assaults the tongue. I like its smokiness from the wood fire, but I'd still rather have my lobster steamed.

Any wood grilling is tricky. Sometimes the kitchen gets it right, but not always. The rockfish is succulent one day, a few moments overcooked to dryness another; its balsamic vinegar sauce seems irrelevant, but the wilted spinach could hardly be better. Two meat dishes fill out the menu, a rib-eye steak that's faintly smoky but too thin to char if you like it pink inside, and a chicken stew that's the sleeper on this seafood menu. Not everyone likes this monotone, messy-looking soup-stew with the old-fashioned house-made noodles known on the Eastern Shore as slippery dumplings. And sometimes it's a bit too watery. But otherwise, it's simply sublime, the chicken so flavorful that the broth is like meat perfume, flour-thickened and studded with mushrooms and fresh peas. It's a stew that will make you welcome winter. Lunch adds authentic po' boys and this city's best hot dog and bun, with sensational french fries.

Johnny's dessert list is inspired: a small collection of house-made ice creams and sorbets, a wonderful, puckeringly tart lemon chess pie, a light chocolate angel food cake (though with a pallid caramel sauce) and sometimes a proudly classic fruit crisp.

Johnny's is still uneven. The servers vary from witty and efficient to overbearing, and the cooking shows the vagaries of a new crew operating in a very small kitchen. With food this unadorned, every flaw counts for a lot. But its biggest problem is that it's as good as it is. The lines are long, and the restaurant takes no reservations. If you hit Johnny's at rush hour, look on the bright side: By the time you get a table, the kitchen will have had more practice.

Turning Tables

Tracy O'Grady is one of our least-known world-class chefs. She's sous-chef at Kinkead's, and has been chosen through competition to represent the United States in the world cooking olympics, called the Bocuse d'Or, in January 2001. To raise money for the practice and travel necessary for O'Grady to compete, a group of friends -- also top chefs -- are joining her to cook on September 27 at Kinkead's. Scott Bryan of Manhattan's Indigo, Ris Lacoste of 1789 here, David Kinkead of Boston's Brasserie Jo, pastry chef Jackie Riley of Tabla in New York, and Kinkead's executive sous-chef, Jeffrey Gaetjen, will help prepare the $150-per-person extravaganza. For reservations, call 202-296-7700. -- P.C.R.