Broccoli is one of the healthiest foods you can eat, a real nutritional powerhouse. Along with a rich supply of vitamins and minerals, notably vitamin C, folate (folic acid), and potassium, it contains the phytochemical sulforaphane, which helps reduce the risk of cancer. In addition, broccoli contains a good amount of beta-carotene. And, unless you drown it in cheese sauce, broccoli is (like all green vegetables) low in calories and virtually fat free.

A close relative of cauliflower, broccoli has grown wild in Mediterranean areas for hundreds of years; domestic broccoli was first cultivated in the United States in the Twenties. Since then, it has become one of the best-selling members of the Brassica genus (which also includes cabbage, Brussels sprouts, and other so-called cruciferous vegetables).

Buying
Fresh broccoli must be picked young to be tender and delicately flavoured. Left growing too long, the plant begins converting its sugar to lignin, a type of fibre that cannot be softened by cooking. (Broccoli that has been stored too long after harvesting also develops lignin.) Overly mature broccoli, no matter how it's prepared, will be tough and woody, and have an unpleasantly strong odour.

Examine the stalks attached to the florets; they should be on the slender side and be so crisp that if you broke one, it would snap cleanly. The florets should be tightly closed and uniformly green; yellowing florets signal that the broccoli is past its prime. Colour is also a nutrition indicator: Florets that are dark green or purplish or bluish green have more beta-carotene and vitamin C than paler florets. The leaves, if any, should have good colour and not appear wilted. Avoid broccoli with soft slippery spots on the florets or with stalk bottoms that are brown or slimy. Fresh broccoli has a clean, "green" smell.

Storage
Refrigeration slows the conversion of sugar to lignin, thereby preserving texture and flavour; keeping broccoli chilled also protects vitamin C content. Store broccoli in an open plastic bag in the bottom of the refrigerator, which will provide the right balance of humidity and oxygen. Do not wash broccoli before storing; although it needs moisture to remain fresh, any water on its surface will encourage spoilage.

Fresh broccoli is at its best if used within a day or two of purchase, but it will keep for up to four days in a fridge. Once cooked, any leftovers may be refrigerated for two to three days in a tightly covered container.

Preparation
Very fresh young broccoli can be served raw as an hors d'oeuvre, or in salads. Its taste and texture, however, don't agree with all palates; in general, most people prefer broccoli cooked. Whichever way you serve the vegetable, first rinse it under cold running water.

Most people cut off and discard the leaves; however, they are edible and contain even more beta-carotene than the florets. If you wish, peel the stalks, which get tougher the longer you keep the broccoli,but remove only a thin layer to preserve the nutrients.

Cooked broccoli should be tender enough so that you can pierce the stalks with a sharp knife, but it should still remain crisp and bright. You can achieve this with any of the methods that follow; however, steaming and microwaving preserve more of the nutrients. Because the broccoli florets tend to cook much faster than the stalks, either split the stalks about halfway up or cut an X in the bottom of each stalk. Another option is to cut off the florets and add them to the pan after the stalks have cooked for two to three minutes. You can also cut both the florets and stalks into smaller pieces for fast, even cooking.