By Chuck Martin
The Cincinnati Enquirer

History: Though some believe walnuts originated in ancient Persia, no one's sure because man has been gathering and eating them so long. The Romans generally are credited with introducing walnuts to Europe. "Walnut'' comes from the Old English "walh-hnuta,'' meaning "foreign nut.'' Now the common Persian walnut is called English walnut, even though some of the best in the world are grown in Grenoble, France, and California. Walnuts native to North America are called black walnuts. Though some admirers maintain the smaller black walnuts have a richer, more intense flavor, they are more difficult to shell than English walnuts, which is why most American growers favor the latter.

Buy: Walnuts are available year-round, but their flavor is best in the fall and winter. They come in three sizes: large, medium and babies. When buying walnuts in the shell, look for those free of cracks and holes. Shelled walnuts should be plump, meaty and crisp.

Store: Walnuts in the shell can be stored in a cool, dry place up to three months. Shelled nuts should be tightly covered and refrigerated for up to six months, or frozen up to a year.

Use: Serve walnuts in salads, savory dishes and desserts. Walnuts complement many cheeses, especially Stilton and other heady blue cheeses. Walnut oil makes distinctive vinaigrettes and salad dressings, and the French saute potatoes and other vegetables in the fragrant oil.

Good for you: Walnuts are high in fat (18 grams per ounce), but also heavy in healthy polyunsaturated fat. Some studies suggest eating walnuts moderately may help lower blood cholesterol. The nuts are also a good source of potassium.

Professional treatment: Brussels Sprouts with Toasted Walnuts is adapted from Chez Panisse Vegetables (Harper Collins; $32.50): Toast chopped walnuts in 350-degree oven until lightly browned, about 10 minutes. Set aside.

Trim, wash and drain Brussels sprouts. Slice sprouts thinly and saute in butter a few minutes. Add toasted walnuts and a little chicken or vegetable stock and continue to cook slowly until Brussels sprouts are tender. Season with salt and pepper.