Open Monday through Friday, noon 2:30 p.m. and 6 to 10:30 p.m.; Saturday, 6 to 10:30 p.m. AE, MC, V. Reservations. Prices: Pastas $6.75 to $8.75; main dishes $6.75 to $15. Full meal with wine, tax and tip $25 to $35 a person.

Just when we thought Washington could not handle one more Italian restaurant, along came Vincenzo to prove us wrong. Vincenzo is far from just another Italian restaurant. It is not a southern Italian restaurant; it serves no lasagne or pizza.It is not another white-sauce northern Italian restaurant; I haven't seen a touch of cream anywhere except in a fruit tart. It does not make its own pasta. It doesn't even serve veal, for goodness' sake.

Vincenzo is an Italian seafood restaurant -- a purist's Italian seafood restaurant. The menu is entirely seafood, in fact, entirely fresh seafood (except some of the shrimp). And, though I expect to continue to hear a barrage of complaints about the restaurant, is is a very good restaurant, with some exceptional food.

The complaints concern Vincenzo's attempt to be authentic, a crusade that has swords drawn over butter and tap water.

Italian buttled water is automatically served, no tap water even on request unless you are the woner's mother. You cannot get butter for your bread; that is considered un-Italian. Don't bother to request cheese for your pasta, for the manager considers cheese incompatible with seafood, excusing the requests with "Asking for cheese is a conditioned response to seeing pasta." (In Italy, however, such requests are likely to be answered with a pat of butter or a dish of cheese rather than an argument.) Salt and pepper are not on the table, but are available on request. Sanka is not. And, in fact, the only coffee is very strong (and, on two my visits, excessively bitter) espresso served in one-half to one-third demitasse cup portions, or cappuccino, wonderful authentic cappuccino. Add to these possible points of conflict some inept handling of reservations during Vincenzo's flying leap into popularity, and the restaurant has frequently landed in the zuppa. While Vincenzo's fans are charmed by the Italian water and unbuttered bread, the unsupecting are at least puzzled and often feel insulted by the refusals. In the ensuing controversy the food itself is sometimes forgotten.

Nobody argues over Vincenzo's appearance. It is quintessentially Italian. Three dining areas, connected by arches, present tile floors and pristine white walls ornamented by only a few small mirrors and a painting on wood. Unpended baskets serve as lamp shades. Rolling carts of antipasti and tarts, baskets of fruit and cheeses furnish the color focus, for the tables are dressed in white, with heavy linens and large, heavy white dishes.

To start, you can drink a bellini, fresh peach juice and champagne, immortalized by Harry's Bar in Venice. One day it was sumptuous, another day a few meager sips in a sherry glass with little peach juice added. The wine list, printed on the menu, is all Italian and all whites, except chianti by the glass. Prices are reasonable for the wines, particularly for the imported house wines.

For antipasti, one could order marinated vegetables from the cart, but they were underseasoned, except for the tuna with white beans. A more accurate barbinger of things to come would be the seafood salad or a half-portion of cold salmon, smooth as cream, spread with homemade golden mayonnaise.

Or start with a half portion of pasta, Usually the choice is linguine, linguine or linguine, imported from Italy and cooked al dente. In fact, one day when I tried it with pesto -- a gloriously fragrant pesto -- the pasta was so al dente it crunched. The same pasta with tomato and crab with basil was the perfect texture, since the hot tomato sauce had cooked it just the tiny bit more that it needed. In any case, the pasta is available usually with clams, mussels or mixed seafoods in garlic-oil parsely sauce that reminds you of the Italian genius for simplicity. Contrasting with this simplicity is risotto, a rare treat around Washington. here a heroic version of dense and chewy rice permeated with the flavors of seafood and wine. It is also a very expensive version and a stunning portion, so order it for two and share it with four.

After that, you need not pay close attention to the menu, for the availability of its entries depends on the seafood supplier, and waiter will apporpriately urge you twards the daily specials. Essentially, the possibilities are grilled fish -- originally dull and dry, but lately impeccably charcoal broiled -- or grilled shrimp, sauteed scallops when tiny bay scallops are available, mixed seafood in one or another wine and tomato stew, squid in tomato sauce and often some seafood and vegetable variation of fritto misto. One day it was cod with zucchini, the cod in large pieces that needed some seasoning, but the batter just the lightest airy crunch and the frying perfectly timed and greaseless; this kitchen knows how to make a superb fritto misto. Similarly, the pesce in brodetto was a luxuriance of lobster, clams, squid and several fish infused with tomatoes, wine and herbs well-laced with pepper but beautifully balanced and light. The stewed main dishes at Vincenzo may be chucks of seafood with bright splashes of Mediteranean herbs -- oregano, fennel, basil -- in light and fresh tomato sauces, or more vividly seasoned fish steaks in thicker tomato sauce with sharp black olives and capers; in any case, the seasoning is talented and the cooking of the fish and seafood is done with great care.

A few dishes miss; cold lobster lacked juiciness and faded under a heavy mayonnaise. But those are exceptions. Criticism is more likely to center on the narrow range of choices. I look forward to Vincenzo expanding its repertoire.

To understand the brilliant simplicity of Italian cuisine, try the green salad. It is just green, but a subtly different mixture, some bitter and others mild, in the lightest slick of fruity olive oil and faintest sharpness of vinegar and salt. It bears the same relation to the typical endive-romaine-watercross-mushroom house salad as Audrey Hepburn to Farrah Fawcett.

Desserts are also simple and very good, usually excellent cold marsala custard foam or one or two fruit tarts, just-made, with circles of raw peaches or berries with a smidgen of custard on a dense, crumbly cookie crust. Fresh fruit salad is available. But consider ending with cheese and fruit, three fine Italian cheeses -- usually including parmeasan and gorgonzola -- with a variety of those fruits you see ripening in the window. Then, that intense bit of espresso or frothy cappuccino.

Service at Vincenzo is generally suave and inclined to flourishes. But the staff has been insufficient to handle crowded moments, and has become flustered and irritated over problems such as overlapping reservations and requests for butter. Waiters do bring extra plates for diners sharing tastes but don't offer to bone a whole fish. Since the menu is confusing, they should take a stronger hand in guiding one through the written as well as the oral menu. A finally, with the wine list nearly exclusively whites, some method needs to be devised to keep them iced; the management uses no wine buckets because condensation drips on the tile floor and makes it slippery.

It should come as no surprise that Vincenzo's prize are high. This is an unstinting kitchen, using the best and freshest of ingredients. The dinner is advised to keep in mind certain peculiarities, however. The half-portions of pasta are priced at two-thirds the whole portions. And daily specials among main courses are often more than $10, higher than the menu items. Furthermore, the same menu is used at lunch and dinner, with the same prices. Considering the quality and attentions, dishes are not over priced; but one is inclined to order freely from those visible temptations and should expect to spend well over $20.

In all, Vincenzo is one of a kind in Washington.