With its uniquely delicate flavour and texture, asparagus is the quintessential "luxury" vegetable. Enjoy it in season, when the price goes down: Asparagus contains a good supply of folate (folic acid), as well as some vitamin C and, in green asparagus, some beta-carotene. Asparagus also contains the phytochemical glutathione, which has antioxidant and anticarcinogenic properties.

Buying
Asparagus deteriorates rapidly when not kept cold, so buy asparagus where it is kept refrigerated or displayed on trays with the stalks standing in cold water. In outdoor markets, the trays should be shaded from the sun.

The best-quality spears are firm yet tender, with deep green or purplish tips that are closed and compact (with no signs of flowers beginning to form); partially open or wilted tips are the most obvious signs of aging. Stalks should stand straight, be green for most of their length, and have a nicely rounded cross-section; flat or twisted stalks are often tough and stringy.

Some people like thick stalks, some people prefer more slender asparagus, but size is not directly related to quality; still, stalks that measure at least 1/2" in diameter at the base are usually preferable. Asparagus is usually sold in bundles, but if you can buy it loose, select spears of uniform size, which will cook evenly.

When deciding on quantity, remember that asparagus loses about half of its total weight once it's been trimmed and cooked. For a main dish, buy half a kilo of asparagus for two people; as a side dish, the same quantity serves three to four.

Storage
Keep fresh asparagus cold to preserve its tenderness and as much of its natural sweetness as possible. Wrap the stalk bottoms in a damp paper towel and store in the refrigerator salad drawer; if you don't have one, put the spears in a plastic bag and store in the coldest part of the refrigerator. It's best to eat asparagus the day you buy it, the flavour can diminish noticeably with each passing day, but it will keep for four to five days if refrigerated.

Preparation
Wash asparagus in cool running water. If the tips have any sand on them, dunk them in and out of water, then rinse thoroughly. Cut or break off the tough bottom ends of the stalks.

Cook asparagus quickly, or it will be unappetisingly limp and discoloured and have a bitter taste. The stalks are done when you can pierce the bottom end with the point of a paring knife. After cooking, lift out the spears and let them drain for a minute on a paper towel. If you plan to serve the asparagus cold, plunge it immediately into cold water to stop it from cooking further.

Steaming: One of the best ways to cook asparagus is to steam it upright in a small amount of water; this way, the delicate tips of the stalks will cook at the same rate as the thick bottoms. Use a tall, lidded pot, or a double boiler (invert the upper portion over the lower). There are also special asparagus cookers designed for this purpose. Or, you can lay the stalks flat in a collapsible vegetable steamer placed in a large skillet.

To handle the asparagus easily, tie the spears into bundles of 10 with kitchen string. Add 2" of water to the pot, bring to a rapid boil, then cover. (You can add a clove of garlic, a slice of onion, or a lemon wedge to the water.) Cooking time: five to eight minutes, depending on the thickness of the spears.

Stir-frying: Cut the spears into 1" to 2" pieces for stir-frying. For an attractive look, cut the asparagus pieces on the diagonal. Cooking time: three to five minutes.

Boiling: Bring about 1" of water to a rapid boil in a large skillet; drop in the asparagus, adding the thickest stalks first and letting them cook for a minute before adding the rest. Quickly bring to a second boil and cook, uncovered. Cooking time: three to five minutes, depending on thickness.

Microwaving: Arrange a bunch of spears in an oblong microwavable dish, with the tips pointing toward the center. Add 60ml of water and cover. Rotate the dish halfway through the cooking time. Cooking time: five to seven minutes.

Roasting: Trim the stalks, then place them in a baking dish and lightly drizzle with a small amount of olive oil. Roast them uncovered at 500ºF/ 250°C / gas mark 9. Cooking time: eight to ten minutes.