Also called Chinese white cabbage, pak choy, pak choi and white mustard cabbage, bok choy is a mild, versatile vegetable with crunchy white stalks and tender, dark green leaves. It resembles a bunch of wide-stalked celery with long, full leaves. Choose bunches with firm, white stalks topped with crisp, green leaves. Bok choy is available year-round in most supermarkets and should be refrigerated airtight for no more than 3 to 4 days. It can be used raw in salads, in a stir-fry or as a cooked vegetable. Bok choy is related to but not the same as chinese cabbage.