THE MULTIPLICATION of Chinese restaurants in Washington's suburbs continues at a dizzying pace. At this rate, Montgomery County alone may soon have more of them than Peking.

But if a thousand Chinese restaurants are flowering, their blooms are by no means equal. What distinguishes the excellent from the ordinary? Ye shall know them by their sauces. At the less accomplished places (which aren't necessarily the cheapest), sauces tend to be characterless, unpleasantly thick and overapplied, and they don't vary much from dish to dish. Salt, sugar and cornstarch seem to be the dominant ingredients, dark brown the usual color. The result is that kung pao chicken isn't much different from the Mongolian lamb and that the inevitable "chef's special sauce" isn't so special after all.

Sauces at the new Hunan Potomac are in a different class. They may not be masterpieces, but they're flavored with some flair, mated intelligently to the dishes with which they're served, not overthickened and ladled on with restraint. And those sauces are a good barometer for the quality of the cooking in general. Although there are no surprises here -- if you've seen a Szechuan or Hunan menu before, you'll know what to expect -- much of what's offered is unusually good.

Hunan Potomac is reasonably attractive and comfortable, and the food is prettily arranged rather than piled on the serving platters. But this is not a Chinese restaurant in the new upscale school, so don't expect hot towels and sorbet between courses, or platoons of waiters dividing up your food for you. On the other hand, the prices are so attractive you probably won't miss those sybaritic touches.

Except for the jellyfish, which has had the texture of rubber bands, you won't go wrong with any of the cold appetizers. Dan dan noodles and bung bung chicken both have good, peppery, peanuty sauces, the sliced beef is lean and nicely marinated, and the crunchy sweet and sour cabbage is properly sweet, tart, hot and gingery. Among the hot appetizers are outstanding steamed dumplings with tender, satiny wrappers and juicy ground pork fillings; reliable, crisp-surfaced Shanghai egg rolls with tiny shrimp and ground pork in the filling; and wonderfully tender, flavorful cho cho beef. But watch out for the fatty, gristly, triple-flavored chicken, and don't expect much from the heavily battered tempura.

If we could write just three words of advice about entrees here, they'd be: duck, lamb, noodles. The duck has been tender, succulent and unusually flavorful, sauces have provided a nice, unobtrusive counterpoint, and the skin, where it's served, has been done to just the right crackle. Among the nonsauced versions, smoked duck is a rare treat, with decidedly more camphor and tea flavor and aroma than most. (Paradoxically, the dish called crisp and aromatic duck is far less aromatic.) Crisp-skinned Hunan-style roast duck is served in a pungent, slightly salty, anise-flavored wash of a sauce that makes a delicious foil for the rich meat. Among the skinless, boneless renditions is duck with asparagus, in which the tender green spears are accompanied by equally thin strips of skinless, boneless duck in a mild, slightly sweet sauce that lets the duck's flavor shine through. Also excellent are shang-cha and Hunan-style sliced duck.

Lamb too is remarkably flavorful, and it's trimmed and cooked beautifully. Hunan lamb is an exceptional dish, with tender, thin-sliced meat and good broccoli in a fine, simple garlic and pepper sauce that tastes mainly of meat juices. Mongolian lamb is more robust, with big strips of scallion and the lightest glisten of oil. Noodles? Look for the ones called "crunchy noodles," which are fried on one side. At Hunan Potomac they're exceptional, cooked so that even the crisp part retains some delicacy and chewiness -- a difficult timing job, carried out to perfection.

Other noteworthy dishes include orange-flavor beef, which is awful in most restaurants but superb here, the meat tender and impeccably trimmed and the lightly breaded surface crisp but still slightly chewy. Be sure to eat slivers of orange peel along with the meat for a wonderful aftertaste. (Orange-flavor chicken is far less interesting.) Sliced pork with chef's special sauce is lovely, the sauce gingery, garlicky and slightly sweet. Shredded pork with ginger and garlic sauce is a bit more subtle and ingratiating, and just as good. Bean cake dishes are exceptionally light and shimmery, and the other vegetable dishes are beautifully done, too.

We did encounter a few disappointments, despite all the excellent dishes. Moo shi pork has been practically devoid of pork, kung pao chicken has been sugar-candy sweet from a massive overdose of hoisin sauce, and the yellow fish used in the whole fish dishes has been decidedly past its prime.

Slip-ups notwithstanding, Hunan Potomac is a first-rate Chinese restaurant with modest pretensions and equally modest prices. One warning: The staff is small and the place seems hardly geared up for a booming business, so wait a little while before you give it a try, or go on a week night. Better yet, do both.