Leek

The leek (Allium porrum) is a biennial herb of the amaryllis family (Amaryllidaceae), 40–70 cm tall at harvest. The white pseudostem, formed by thick leaf sheaths clasping each other, is 3–6 cm across and 15–25 cm long, and is the main edible part. The leaves are broad, strap-shaped and soft, arranged in two rows, green to greyish-green. The inflorescence is a round umbel atop a 1–1.5 m scape (uncommon on early-harvested plants), of many small white to pale-purple flowers. The roots are fibrous from a flattened basal disc. Unlike the onion, the leek does not form a round bulb but swells only slightly at the base. Its taste is mildly pungent and sweet; it is eaten raw, braised, stir-fried or in soups.

The leek originates in the Mediterranean, was domesticated by the ancient Romans and spread across Europe from the Middle Ages; today it is grown widely in Europe, North America and temperate Asia. In Vietnam it is grown on a small scale in cool areas such as Da Lat and Sa Pa, mainly for Western cuisine (leek soup, braised and pan-fried dishes). The white pseudostem is sweet, mildly pungent and crisp; the young green leaves are also edible. Nutritionally, leeks are rich in fibre, vitamins K, C and A and low in calories. The sulphur compounds (allicin, ajoene) and flavonoids (kaempferol) confer antibacterial and antioxidant activity and support cardiovascular health in recent studies.