This week's look at what's bountiful, new or even mysterious in the produce aisle.

Watercress is probably best known for its star status at afternoon tea. Thin slices of white bread, slathered with sweet butter and then filled with the peppery green are almost a requirement at the mid-afternoon meal. But watercress is more than sandwich stuffing. It has history. References to watercress go back to Roman times, when it was known more for its medicinal value than its culinary merits. Touted at one time or another as a cure for almost everything that ails, today it's recognized as a good source of vitamin C and as a spicy herbaceous green.

Watercress livens up almost any dish it touches. Add a cup or two to an ordinary potato soup and you'll note an amazing difference. The same goes for dull salads. And watercress, with its clean, clear taste, makes a delicious soup or salad on its own. Or, use it in place of spinach in stuffings and fillings. Watercress, which grows beside streams, has a natural affinity for fish. Make it into a quick sauce or saute and use as a bed for fish fillets or fish steaks. As a garnish, it's also a good alternative to parsley.

Whatever use you have in mind, resist the urge to pick and eat any wild watercress you happen upon. Because it grows by water, it's particularly vulnerable to waterborne bacteria and the like.

Buying and Storing: One glance will tell you all you need to know. The leaves should be fresh looking and crisp with a deep green color. Small patches of yellow leaves are fine, but these leaves should be removed.

To store, rinse the leaves, shake off any excess water and place in a plastic bag. Refrigerate until ready to use. Don't let it sit too long--five days in the refrigerator is the outer limit.

Cleaning: Rinse again before using. Discard any yellow leaves and the tough lower stems.

Cooking: Watercress doesn't need heat to bring out its flavor. When cooking, go easy and quick. Add to soups in the last five minutes of the cooking time. Toss into stir-frys, again at the end of the cooking. Steam briefly and use a bed for fish or chicken. Puree and swirl into mashed potatoes. Use as the green in stuffings for mushrooms, chicken breast and all kinds of meat roulades.