Long, crisp, white stalks support dark green leaves. Bok choy hearts have a sweet taste, and stalks and leaves maintain crispness after cooking. It also can be eaten raw. Also known as celery mustard, Chinese mustard and pak choy, this vegetable is good in stir-fry and can be used as a substitute for Napa cabbage. It is available year-round from California and Arizona, depending on the season.