It’s easy to think of kohlrabi as a root vegetable, but it isn’t. It’s a brassica with the base of its stem swelled into a slightly turnipy globe. When you’re buying them – farmers’ markets, farm shops and some of the more adventurous supermarkets are good hunting grounds – look for firm, unblemished bulbs with juicy green leaves with not a hint of yellow to them. Kohlrabi is called out because it’s easy to grow—many farmers plant it—but until recently, it hadn’t infiltrated mainstream grocery store shelves. These days, it’s much easier to find kohlrabi; if you haven’t cooked with it, chances are you’ve at least heard of it.