Nothing predictable in this summer's new salads

Salads have come a long way. Certainly we thought the mixed salad green was the epitome when compared with cottage cheese with pineapple, and the tuna, chicken, and Waldorf specials of the past few decades.

Today we have cold pasta salads and warm meat salads, smoked chicken and turkey, and a long list of new ingredients never put into a lettuce leaf before.

The new salads appear to be a sort of a spinoff from the ''nouvelle cuisine, '' a trend toward lighter foods, smaller servings attractively arranged, and unusual combinations of ingredients.

There are new greens as well as new ingredients. Three of the current popular ones are mache, arugula, and radicchio. Mache is the French name for what we call lamb's lettuce or corn salad; radicchio and arugula are Italian. Arugula is also called rocket or roquette.

These are easy for the home gardener to grow but expensive in specialty markets and sometimes difficult to find - although a farmer's market is a good place to look.

Often a small grower at a farmer's market will have a few unusual or newly popular herbs and greens. If you don't see them, inquire.

Lamb's lettuce is familiar to some as a wild green. A smooth, oval, light green leaf, it has a delicate texture and is good in a mixed green salad. It is especially nice with a walnut oil dressing, served with a ripe pear and creamy white goat cheese.

Rocket, also called arugula, rugola, roquette, or rocket cress, has a tart, mustardy flavor, some say. Others say its strong flavor is like horseradish or peanut butter or sesame seeds.

It is good mixed with other lettuces or by itself tossed with garlic and a strong olive oil and wine vinegar. It's easy to grow and well worth it, since a package of seeds costs about 65 cents, compared with a $4 salad in a posh restaurant.

Radicchio, from Italy, is one of a large number of red chicories which I have seen selling for from $4 to $6 a pound. Ed Giobbi, a food writer and gardener from Katonah, N.Y., is probably responsible for its introduction in several New York City restaurants. He also encouraged me and food writer Pierre Franey to grow it.

The first year it produces a tender green leaf which turns red in early fall, eventually forming small heads of beautifully colored, crisp, slightly bitter leaves.

Varieties differ in their tolerance of frost. Red Verona and Treviso (which doesn't form a heart) can be lifted and forced like Witloof Chicory (Belgian endive). Another variety is called Variegated Castelfranco.

Most supermarkets today carry a good selection of greens even without the newer ones. Lettuces in good supply include Romaine and Cos, with large crisp ribs and a sharp, curly leaf; Bibb and Boston varieties; broad-leaf escarole; and curly, loose-leaf chicory.

Then there is spinach, now popular in salads; dandelion greens; watercress; Belgian endive; nasturtium leaves; and parsley.

Western iceberg lettuce should not be forgotten, with its wonderful crunchy texture and ability to stay crisp longer than all the others.

Almost any kind of cold vegetable is acceptable in salads today, especially if it's crisp. Favorites are raw or quickly blanched cauliflower, broccoli, snow peas, or green beans. Some cooks add thinly sliced sticks of parsnip, rutabaga, or turnip.

Cold dishes need more seasoning than hot foods, and you'll find that tiny shreds of lemon and orange, or sesame seeds, pine nuts, carraway, or fresh mint, add flavor.

Soaked raw wheat, cold rice, and tiny cold boiled potatoes are also apt to appear on the salad plate along with cooked meat or fish.

''Composed'' salads are now familiar. These are made of a careful selection of ingredients, marinated separately so the flavorings are just right, and arranged attractively on the plate.

Dressings can be different, too, with one of the many herbed vinegars teamed with salad oil or with a special oil such as walnut oil.

Despite the new kinds of salads, many of the old favorites - potato salad and fish and chicken mixtures - are still around. And fresh fruit, sliced and served with a creamy dressing made with sweet or sour cream or creme fraiche or a light oil dressing, is still a refreshing and colorful addition to any summer meal.

Seeds for fall planting for the above new greens are available by mail from the following companies:

Epicure Seeds, Box 23569, Rochester, N.Y. 14692.

Nichols Garden Nursery, 11190 North Pacific Highway, Albany, Ore. 97321.

Le Jardin du Gourmet, West Danville, Vt. 05873. Rocket and Tomato Salad 4 ripe tomatoes 1 cup young rocket leaves 1/4 cup olive oil or walnut oil Salt and pepper to taste

Slice tomatoes and arrange on platter or individual salad plates, overlapping slightly. Sprinkle with salt and pepper, then rocket leaves, then add a liberal amount of olive oil. Add more salt and pepper if desired. Alice Water's Lamb's Lettuce and Rocket Salad 4 handfuls lamb's lettuce and rocket 1/2 cup virgin olive oil 3 tablespoons red wine vinegar 1 teaspoon Dijon mustard Salt and pepper Optional: 12 hard-cooked eggs

Wash lettuces and dry well. Make a dressing with next 4 ingredients. Dress greens with some of the vinaigrette.

Arrange greens on salad plates and garnish with hard-cooked eggs. Greens and Red Pepper Salad 1 large head Romaine lettuce 1 bunch rocket (arugula) 1/2 pound fresh mushrooms 2 sweet red peppers Vinaigrette

Wash and dry lettuce. Remove stems from mushrooms and save for another use; wipe mushroom caps. Cut out stems, ribs, and seeds of pepper and slice into fine julienne strips.

Refrigerate vegetables. To assemble, tear lettuce in bite-size pieces and divide among 6 salad plates. Slice mushrooms and sprinkle over greens, then add peppers.

Drizzle each plate with vinaigrette and serve immediately. For a large salad combine in salad bowl and toss with dressing before serving. Serves 6. Basic Vinaigrette 1 clove garlic 1/4 teaspoon salt 2 tablespoons wine vinegar 1/4 teaspoon Dijon mustard (optional) 9 tablespoons olive oil Freshly ground pepper

Peel garlic and mash with salt. Stir in vinegar and mustard. Gradually beat in oil with a whisk. Add pepper. Makes 2/3 cup, enough for salad for 10 people.

This dressing can be varied by using different oils or different vinegars. Beet Salad With Mint 2 cups cooked, sliced beets 6 tablespoons raspberry vinegar 1 cup olive oil Salt and pepper to taste 2 tablespoons chopped fresh mint

Cook beets until tender. Cool and slip off skins with the help of cold water. Slice into thin rounds.

Combine vinegar and olive oil with seasonings. Toss sliced beets with the vinaigrette and marinate at room temperature about 1 hour.

Line a platter with green lettuce and add the marinated beets. Top with chopped mint.