VINCENZO -- 1606 20th St. NW. 667-0047. Open: for lunch Monday through Friday noon to 2 p.m., for dinner Monday through Saturday 6 to 10 p.m. Closed Sunday. AE, MC, V. Reservations suggested. Separate non-smoking section. Prices: lunch appetizers $7 to $9, entrees $15; dinner appetizers $7.75 to $9.75, entrees $16.75 to $24.75. Full dinner with wine, tax and tip about $55 to $65 per person.

ALL IS FORGIVEN. VINCENZO IS back on track.

After years of renovation, this long-admired Italian seafood restaurant finally completed its expansion this spring. And in its wake I heard numerous complaints. When I revisited in the spring, I had plenty of complaints myself. So I gave it some months to recover from the changes and then returned a couple of more times. It's back on my list of Washington's finest Italian restaurants, though with a few more reservations.

No, the menu has not expanded to in- clude meat. It is still all fish and sea- food, though the wine list is now, oddly, half reds. But even if you don't drink red wine with fish, the list is an intriguing collection, and the prices are not outlandish.

And I know I'm crotchety when it comes to restaurant prices, but so is everyone nowadays. The mightiest restaurants in Washington have trimmed their tabs, and every restaurateur is aware that the free-spending days have waned. Yet Vincenzo boldly charges $24.75 for a third of its main-dish choices, and while pasta as an appetizer is $9.75, a main-dish portion at dinner is $18.75. That's for the likes of factory-made noodles with a little swordfish or crab and tomato sauce, or even with just olives, capers and anchovies. At Vincenzo you are likely to find finesse but not generosity.

Vincenzo is the kind of restaurant where you want to have a list of what to order and what to ignore; you could miss the point of this kitchen if you choose blindly.

Italian restaurants always present a struggle: order antipasto and go on to a main dish or pasta as the main dish, or start with pasta and go on to meat or seafood? You could precede a main dish with both antipasto and pasta, but few of us these days eat so heavily.

At Vincenzo the antipasto is worth forgoing something else. The antipasto misto is a plate of authentic and delicious morsels -- roasted red peppers rolled around tangy fish salad, white beans, a brightly fresh seafood salad with tiny scungilli, marinated vegetables, tiny purple olives stuffed with capers. These days the tastes are fresh and the flavors are pungent enough to wake up your appetite as a first course is meant to do. More unusual and also delicious is a plate of polpettini misti -- tuna, crab and fish cakes -- each with its own sauce and each sauce a splash of vivid flavor. There are also clams in tomato sauce or baked clams, seafood salad and vegetable salads.

Most of the pastas are very good factory-made noodles with simple sauces: clams with red or white sauce, olives with capers and anchovies, fish or seafood in tomato sauce. A few of the pastas are house-made, and these are the most interesting. Fish ravioli, for example, have a handmade character and a distinguished filling of minced fish. Fazzoletti al pesto is sheets of homey dough that look like cloth draped on the plate, just smeared rather than drenched with pesto. After the endless pesto dishes being offered in today's restaurants, I had given up on this basil/ pine nut/cheese puree, but it tastes fresh and new at Vincenzo, not the usual perfumed baby-food-smooth paste. Here it is a faintly grainy coating with the crunch of minced pine nuts, basil and parmesan in a green aromatic slick of excellent olive oil.

Tomato sauces, on the other hand, are smooth and pasty, strong enough to eclipse the seafood flavor and likely to bore you halfway through the noodles. The spicy crab meat sauce hasn't the electric taste it once had, and rigatoni with swordfish sauce is thick and so heavy that the swordfish might as well be tofu.

I'd bypass the tomato sauces in the main dishes too. Shrimp with capers and tomato has a more lively interplay of flavors than most of the sauces, but the shrimp don't shine in it. Zuppa ai frutti di mare drowns out its lovely clams and chunks of lobster in the dense, strong sauce. The preparation that lets Vincenzo's high-quality seafood shine is grilling. Grilled grouper with green sauce is the star of the main dishes I've tried. The thick fillet is flawless in its flavor and its cooking, striped by the grill and accompanied by a glorious tangy green sauce of herbs, olive oil and vinegar, Italy's answer to salsa. Grilled swordfish is more delicately flavored with oregano and the fillet is thinner, but it still displays greatness, as does the saute'ed swordfish covered with purple olives. Grilled dishes include mixed fish, a brochette, marinated red snapper and huge sea scallops -- which are a little undercooked but a handsome preparation otherwise. Swordfish is also sliced thin, rolled with an olive-spiked stuffing and grilled, the best of the complicated dishes.

Vincenzo also fries seafood superbly, crisped by the thinnest veil of flour coatings and not the least bit greasy. Soft-shell crabs are tiny and plump, squid is tender, shrimp are flavorful, and the mixed fried seafood dish includes juicy fish and shards of zucchini, perfect after a squeeze of lemon is added.

Most main dishes are garnished with a little grilled zucchini, a chunk or two of cooked fennel and a couple of boiled potatoes. It is all quite simple and generally very good.

I've heard complaints about the portions of fish, but either the portions just looked small because they are cut thick and therefore don't cover much of the plate, or Vincenzo has increased their size; I found that they don't look imposing, but they are sufficient.

Still, you'll probably have room for dessert. And Vincenzo makes ordering dessert worthwhile. The peach sorbetto has more intense flavor than any frozen fresh peach dessert I've tasted, and is refreshingly tart. Coffee sorbetto is unusual, with all the powerful taste of Italy's granita di caffe and the fine airy texture of France's sorbets. You're likely to find lemon, apricot and raspberry sorbetto as well. On the heavier side, there are cream puffs filled with honest custard and armored with hardened bittersweet chocolate, the kind of dessert chocolate lovers fight over. Cannoli are house-made, and while the shells are too thick, the filling is the best I've found outside Sicily. Finally, the espresso -- an authentic tiny half-cup of not-quite-hot bitter elixir -- would challenge the strength of any that a Rome espresso bar could offer.

I wish Vincenzo weren't so pricey. I miss the original spicy crab pasta and could do without most of the restaurant's tomato sauces. And I long for some of the rare seafood the restaurant used to procure. Still, the dining room has expanded for good reason: At Vincenzo you can still find Italian seafood that illustrates the greatness of impeccably simple cooking.