Kohlrabi

Kohlrabi (Brassica oleracea var. gongylodes) is an annual or biennial herb of the mustard family (Brassicaceae), 30–50 cm tall. Its defining feature is the stem swelling into a round or slightly flattened bulb right at ground level, 5–10 cm across, with pale-green or purple skin and ivory-white, crisp, juicy, mildly sweet flesh. The leaves are large, cabbage-like, grey-green, long-stalked, spreading in a rosette around the bulb; young leaves are edible. Left past its season the plant bolts and opens small four-petalled yellow flowers, typical of the mustard family, then forms siliques with seeds. The edible part is the stem bulb; Vietnamese cooks peel it and boil, stir-fry, salad or pickle it.

Kohlrabi originated in Europe, selected from wild cabbage (Brassica oleracea) in Germany and northern Europe from the 16th century; today it is grown across Europe, Asia and North America. In Vietnam it is a typical winter-spring vegetable of the northern lowlands, grown widely in Hanoi, Hai Duong, Hung Yen and Da Lat. The bulb is boiled and dipped in sesame salt or kho quẹt (caramel fish sauce), stir-fried with garlic, julienned into carrot-kohlrabi salad, or pickled to serve with pork rolls; the young leaves are boiled too. Kohlrabi is rich in vitamin C, potassium and fibre, low in calories; folk use supports digestion, cools the body, and suits dieters. The bulb keeps well after harvest.