Once strictly a specialty food, this native American vegetable is becoming more widely available in markets everywhere. "Jerusalem artichoke" has been its common name since the 17th century. The plant has no connection to either Jerusalem or artichokes, but is, in fact, a type of sunflower. So, why is it called a Jerusalem artichoke? One story is that the French explorer Champlain sampled the vegetable in the early 1600s in Massachusetts, where it was cultivated by Native Americans, and he likened its taste to that of an artichoke. Some years later, after they had been introduced to Europe, the English added Jerusalem, perhaps a corruption of girasole (an Italian word that means sunflower).

The Jerusalem artichoke is actually a tuber, or underground stem, that resembles a small nubby potato or a piece of ginger root. But it has a sweet, almost nutty taste and a crisp texture that is quite distinctive. A versatile vegetable, it can be eaten raw or cooked, and added to all types of dishes. Like potatoes and other tubers, the Jerusalem artichoke stores carbohydrates, but most of them are in the form of inulin, a sugar that can sometimes cause flatulence. (If you have never sampled Jerusalem artichoke, you should eat it in small amounts until you are able to determine how your body will react to it.) The vegetable is also an incomparable source of iron, almost on a par with meats, yet without any fat content.

Buying
Look for clean, firm tubers with unblemished skin, which may be as glossy and tan as the skin of ginger root, or a matt brown. They should not show a greenish tinge or any sign of sprouting or mould. Choose the least knobbly tubers, and be sure they are not limp or spongy. If you're planning to cook them whole, choose tubers of similar size.

Storage
Wrap them in a plastic bag, seal, and store in the refrigerator . They will keep for up to two weeks. If you have a cool, dark storage place, such as a dry cellar, they can also be kept there.

Preparation
Scrub tubers well with a vegetable brush. It's better not to peel them, as much of their nutrient value lies just beneath their thin, edible skin. If you choose to do so, however, use a vegetable peeler. Should the small areas of skin around the knobbly portions prove difficult to remove, just leave them on. (Immediately immerse peeled or cut-up jerusalem artichokes in cold water acidulated with lemon juice or vinegar, or their flesh will discolour.) If you are boiling or blanching the tubers, you may remove the skin after cooking; it will peel or rub off easily. Do be aware, however, that when cooked unpeeled, the flesh of jerusalem artichokes will darken because of their iron content.

Jerusalem artichokes can be prepared and served in many of the same ways as potatoes, and can be used in place of parsnips and turnips in some recipes. Whatever cooking method you choose, check frequently they can turn mushy in seconds once they reach the point of tenderness. Don't cook them in aluminum or iron pans, as their white flesh will darken.