UGLY IS ONLY skin deep in many a fruit and vegetable. Blemished produce need not be discarded. The smart cook simply cuts away the blemish and uses what's left, chopping or shredding it into cooked dishes, says Francis Lay, an Arlington County extension agent who specializes in horticultural problems. Blemishes won't hurt you, he says, they're just not pretty.

That's got to be a relief for the home gardener, considering all the garden damage this year's wet spring has caused. Just when you thought it was time to start picking squash, cabbage, tomatoes, cucumbers and greens, suddenly there are problems. Plants are wilting, tomatoes have black spots, cabbage is soft.

Water and tiny garden insects are at the root of the problem, says Lay. Too much or too little water causes the brown spots (early blight) and black spots (blossom end rot) that turn up so often on tomatoes. While those tomatoes won't look beautiful sliced into rounds for a buffet, still they can be chopped into sauces and salads and cooked into stews or shredded into Chinese stir-frys.

Tomatoes are also vulnerable to a number of wilts, Lay says. Three in particular are quite common in the Washington area: One wilts the leaves but doesn't affect the fruit at all. Verticillium fungi and fusarium fungi, however, cause the plant to eventually collapse and die. Should this happen in your garden, "the tomatoes are safe to eat," says Lay, "provided there are any on the plant at this point."

Another garden problem, the insect population, is on the rise this year. These tiny critters pay visits to every garden in town and will take over if left uncontrolled, Lay says. You may have already seen the results of their feasting in the form of tiny holes on leaves, or tiny trails in the roots or bulbs of underground crops. Simply wash the leaves in warm water and cut away the trails in roots or bulbs.

The cucumber beetle actually changes the taste of some fruits and vegetables. Melons, cucumbers and an occasional squash are their favorite prey, Lay says. Even though they won't hurt you, and they are invisible since they live in the vine, they leave these crops bitter and inedible.

While the thought of garden critters and rain-soaked fungi doesn't strike one as particularly elegant eating, the following recipes make lovely use of these marred crops.

Stuffed flank steak tastes good hot or cold and it looks beautiful with swirls of red and green vegetables and melted cheese. The Chinese curried stir-fry is a different and quick after-work meal, fit for a guest and designed to keep you out of the kitchen. Once the chopping is done, the cooking only takes 10 minutes. The zucchini quiche is pretty, with layers of cheese supporting green and yellow squash. The addition of chopped fresh sorrel gives the dish a refreshing, slightly sour taste. STUFFED FLANK STEAK (4 servings) 1 1/2-pound thin flank steak, about 12-inches-long by 8-inches-wide 1 tablespoon soy sauce Black pepper 1 large tomato, chopped 3 lettuce leaves, shredded 3 scallions, chopped, greens included 1/2 cup romano cheese, grated 1/2 cup parmesan cheese, grated

Rub flank steak with soy sauce and sprinkle with black pepper. Put aside. Mix together tomato, lettuce, scallions and cheeses. Spread on short end of steak and roll up jelly-roll fashion. Secure roll with twine or hold together with toothpicks. Spread remaining filling in the bottom of baking dish, large enough to hold the rolled-up steak. Bake at 350 degrees for 25 to 30 minutes. Cut into 8 1-inch slices and serve 2 to each person. CHINESE CURRY STIR-FRY (4 to 6 servings) 1 tablespoon curry powder 1 teaspoon salt 1 tablespoon sugar 1 teaspoon grated ginger 1 teaspoon soy sauce 1 tablespoon rice wine 1 tablespoon cornstarch 1/2 cup chicken stock 1 dried hot red pepper, crumbled 2 tablespoons peanut oil 2 cloves garlic, minced 12 green beans, snapped into bite-sized pieces 1 small white onion, cut in half then thinly sliced 1 tiny zucchini, sliced 1 tiny yellow squash, sliced 6 medium leaves swiss chard, torn into small bits

Mix together curry powder, salt, sugar, ginger, soy sauce, rice wine, cornstarch, chicken stock, red pepper and set aside. Heat peanut oil in a wok. Add garlic, toss 30 seconds. Add green beans and onion and stir-fry 1 minute. Add zucchini and squash; stir-fry 2 minutes more. Add swiss chard and stir-fry for 1 minute. Remove from pan. Add sauce ingredients to pan and cook, stirring, until translucent. Return vegetables to pan, heat through and serve. SQUASH QUICHE (4 to 6 servings) Crust for a 9-inch quiche pan 1/2 cup grated swiss cheese 1/2 cup grated gruyere cheese 1/2 cup grated cheddar cheese 1 tiny zucchini, peeled and sliced 1 tiny yellow squash, peeled and sliced 1 small onion, diced 1 tablespoon olive oil 2 eggs 1/2 cup sour cream Salt and pepper to taste 1 teaspoon fresh savory, chopped 1 teaspoon fresh parsley, chopped

Mix cheeses together and sprinkle 3/4 cup in bottom of crust. Saute' zucchini, yellow squash and onion in olive oil for 3 minutes (just to get them started cooking). Spread on top of cheese. Mix together eggs, sour cream, remaining cheese, salt and pepper to taste, savory and parsley and spread on top of quiche. Bake in a 350-degree oven for 35 to 40 minutes or until set and a knife inserted in the center comes out clean.