This knobbly, alien-looking, subtly flavored vegetable is a member of the brassica family. A similar size and shape to the turnip, it is not in fact a root, but the swollen above-ground stem of the plant. It is available all year round, but starts turning up at farmers' markets and vegetable gardens in July and August in the Northern Hemisphere. It is easy to grow, can be stored for a long time and is easy to cook with too – or eat it raw, as in Luke Nguyen's Vietnamese-style Beef and Kohlrabi salad. Learn more about kohlrabi in Elizabeth Schneider's 'Vegetables from Amaranth to Zucchini'.