NEXT TIME YOU buy tomatoes, look for the pile with the bruised ones. Carefully inspect their tops; they should be hard, yellowish green, irregular in shape and scarred. A few cracks will mar the smooth and rich red skin.

This is the pile of homegrown vine-ripened tomatoes you should choose your purchase from, not the million-pound, towering stack of pinkish orange "square rounds," as the professionals call those identical and cosmetically perfect tomatoes, the ones designed to hold their own on a conveyor belt rather than in a salad.

All of this is meant to emphasize that there is nothing wrong with a blemish, and that an occasional bruise on a vine-ripened tomato is natural. Just take a few home for dinner and you'll understand why you should seek them out.

During the summer months, Washingtonians are lucky because they have roadside stands and even supermarkets that sell local, down-home, vine ripened tomatoes. For those seeking new ways to use this year's crop, the recipes below offer five fresh ideas: a sherbet to serve as an appetizer, a tomato conserve that can be used like a chutney, a brilliantly colored salad flavored with asiago, a fresh tomato sauce that goes well on vegetables or pasta, and finally, a nearly perfect ketchup. TOMATO SHERBET (6 servings)

This unusual sherbet is a cool and refreshing new way to use tomatoes this summer. Serve it as a first course before a light entree, to guests who are gastronomically adventurous. 3 pounds ripe tomatoes 1 small onion 1 tablespoon chopped fresh basil or 1 teaspoon dried 1 tablespoon chopped fresh marjoram or 1 teaspoon dried 1 tablespoon tomato paste Juice of one lemon 2 to 4 tablespoons sugar

Core the tomatoes, then chop roughly. Peel and coarsely chop the onion. Combine the tomatoes, onion, basil and marjoram in a saucepan. Bring to a boil, then reduce heat, partially cover, and simmer over low heat for about 20 to 25 minutes until the mixture is very soft. Be sure to stir often to prevent scorching.

Pure'e the tomato mixture in a food processor or blender, then press through a sieve. Add the tomato paste to heighten the flavor, the lemon juice, and finally stir in just enough sugar to gently sweeten the mixture.

Pour into the canister of an ice cream freezer and freeze according to the manufacturer's directions. FRESH TOMATO CONSERVE (Makes 8 1/2-pints) 5 pounds ripe tomatoes, peeled and cored 7 cups sugar Juice of 2 lemons Juice of 2 oranges 1 teaspoon ground cinnamon 1/2 teaspoon ground cloves 1 cup raisins 1/2 cup candied orange rind, coarsely chopped 1/2 cup candied ginger, coarsely chopped

Chop the tomatoes coarsely and place in a heavy-bottomed saucepan with the sugar, citrus juices and spices. Bring to a boil over medium heat. Reduce heat and simmer, stirring frequently to prevent burning, until mixture becomes very thick, about 1 hour. Add the remaining ingredients and cook 10 minutes longer, then spoon into jars and seal. ROBIN'S TWO TOMATO SALAD (6 to 8 servings)

This bright, colorful salad is full of the tastes of summer. The oil and vinegar dressing is flavored with the sharp, almost pungent taste of asiago, one of Italy's great but little-known cheeses. Roquefort would make a nice substitute if asiago is not available. 3 medium ripe red tomatoes 3 medium ripe yellow tomatoes 1 large bunch scallions, both green and white parts, coarsely chopped 5 or 6 large fresh basil leaves, roughly chopped 1 small bunch fresh parsley, washed and finely chopped 1 cup good-quality olive oil 1/4 cup strawberry or raspberry flavored red wine vinegar 6 ounces asiago or roquefort cheese Freshly ground black pepper

Peel and core the tomatoes only if you wish; it really isn't necessary for this salad. Quarter the tomatoes and place in a large mixing bowl. Add the scallions, basil and parsley. In a blender or food processor, combine the oil, vinegar and cheese and process until well blended. Add a very generous amount of black pepper to the dressing and blend well. Dress the tomatoes and serve immediately. FRESH TOMATO SAUCE (Makes 1 quart)

This wonderful, fresh sauce is good with fish or vegetables, or on pasta. 4 tablespoons olive oil 1 medium onion, peeled and chopped 3 pounds ripe tomatoes, peeled, seeded and chopped 2 tablespoons finely chopped fresh basil, or 1 teaspoon dried 2 tablespoons finely chopped fresh parsley Salt (optional) Freshly ground black pepper

Heat the oil in a heavy-bottomed saucepan over medium heat. Add the onion and saute' until very tender and translucent. Add the tomatoes, herbs, salt if desired, and freshly ground black pepper. Simmer for 10 to 15 minutes. Serve. ELIZABETH COLCHIE'S HOMEMADE KETCHUP (Makes 8 1/2-pints) 8 quarts vine-ripened tomatoes 2 medium onions, peeled and chopped 1 large sweet red or yellow pepper, coarsely chopped 1/2 cup celery and celery leaves, chopped 4 garlic cloves, chopped 2 cups cider vinegar 1/2 cup granulated white sugar 1/3 cup brown sugar For the cheesecloth: 1 tablespoon mustard seeds 1 tablespoon whole allspice berries 1 cinnamon stick 1 tablespoon black peppercorns 2 crumbled bay leaves 1 teaspoon whole cloves 2 tablespoons whole coriander seeds 1/4 teaspoon celery seed 1/4 teaspoon dried red pepper flakes

Core the tomatoes, then cut into quarters. Boil in a large pot for about 30 to 40 minutes until the tomatoes are soft. Measure out 4 quarts of the cooked tomatoes and set the remaining tomatoes aside for another use. Add the onion, sweet pepper, celery, garlic and vinegar and bring back to a boil.

Tie the seasonings listed above securely in cheesecloth. Add to the tomato mixture with the sugars and cook over medium high heat, stirring frequently, until ketchup thickens, about 20 to 25 minutes depending on the water content of the tomatoes.

Press the ketchup through a large sieve, then again through a medium sieve, and finally through a fine sieve. If you feel the ketchup needs salt, add a sufficient amount at this point. If the ketchup looks too thin, boil again until it reaches the desired thickness. Remember, it will thicken as it cools.

Seal in sterile jars according to the manufacturer's directions.