Mustard greens (Brassica juncea) are peppery leafy greens in the cruciferous vegetable family, closely related to kale, collards, cabbage, and broccoli. Their flavor ranges from mildly spicy in young leaves to distinctly pungent and mustard-like in mature greens. Mustard greens are particularly rich in vitamin K1 and provide carotenoids, vitamin C, calcium, potassium, fiber, and protective plant compounds called glucosinolates. When the leaves are chopped or chewed, these compounds can be converted into isothiocyanates responsible for some of their characteristic pungency and biological activity. Mustard greens can be eaten raw when young or sautéed, steamed, braised, added to soups, or incorporated into curries and stir-fries.