Versatile watercress isn't just a dainty drawing room delicacy

If you have only used watercress as a decorative garnish, you are missing one of the most welcome harbingers of spring, as eagerly awaited as the first dandelions, fiddlehead greens, and rhubarb. The pungent cress that fills those thin, elegant sandwiches is a member of the cruciferae family. It grows best in running water - rivers and streams - and while this nippy herb may appear delicate, the people who grow it can count on a constant supply, for it spreads rapidly.

In early spring, the watercress leaves have a mildly pungent flavor, but as summer comes they become more peppery. Watercress can be harvested until the first frost. To store it, treat it like a bouquet, submerging the stems in water, and cutting off a little each day. Keep it in the refrigerator, covered with a sealed plastic bag.

No watercress recipe file would be complete without watercress sandwiches and watercress soup. The late James Beard, a respected authority on cooking, said that his idea of a really good watercress sandwich consists of ``thinly cut brown bread, whole wheat, oatmeal or barley grain ... with good, unsalted butter, masses of fresh watercress, and just a sprinkle of coarse salt.'' Another suggestion is watercress, cheese, alfalfa sprouts, tomatoes, and mayonnaise. Creamy Watercress Soup 3 tablespoons butter or margarine 2 bunches watercress, washed and chopped 1 onion, minced 1 bay leaf Pinch of thyme 2 medium-size potatoes, peeled and diced 3 cups canned chicken broth Salt and pepper to taste 1/2 teaspoon paprika 1/4 cup heavy cream Parsley (garnish)

Melt butter in saucepan. Add watercress, onion, bay leaf, and thyme. Cook until cress is limp. Add potatoes and chicken broth to cover. Simmer until potatoes are tender. Press through a sieve. Add seasonings and cream. Heat through; garnish with parsley. Serves 6 to 8. Saut'eed Watercress for Two 2 tablespoons salad oil 1/4 pound fresh mushrooms, sliced 8 cherry tomatoes, halved 1 bunch watercress 1/2 teaspoon salt 1/4 teaspoon lemon-pepper seasoning

In 10-inch skillet over medium-high heat, cook mushrooms in hot salad oil until tender. Add remaining ingredients. Cook, stirring, until tomatoes are heated through and watercress just wilts. Serves 2. Dainty Rolled Watercress Sandwiches 1/2 cup mayonnaise 3 ounces cream cheese, at room temperature 4 tablespoons unsalted butter, at room temperature 3/4 cup finely chopped watercress Celery salt to taste 48 thin slices white bread, crusts removed

Combine mayonnaise, cream cheese, butter, watercress, and celery salt in small bowl. Blend well with wooden spoon. Flatten each bread slice with rolling pin. Spread about 1 teaspoon of filling over each slice, then roll up jelly-roll fashion. Cut each sandwich in half crosswise. Refrigerate, wrapped tightly in plastic, until ready to serve. Makes about 8 dozen.

In France, watercress is the inevitable accompaniment to roast chicken. Watercress Sauce 1 13 1/4-ounce can chicken broth 3 tablespoons all-purpose flour 2 1/2 cups coarsely chopped watercress 1/2 teaspoon salt (optional) 1/8 teaspoon pepper

In 11/2-quart saucepan over high heat, heat chicken broth to boiling. Meanwhile, in cup blend flour and cold water with a fork until smooth. Reduce heat to medium. Gradually stir mixture into hot broth. Cook, stirring constantly, until sauce is smooth and thickened. Stir in remaining ingredients. Simmer 2 minutes. Serve hot with hot poultry. Makes about 2 cups.