Black Mustard Seed
From the plant known as Brassica nigra. Used commonly in South Indian cooking in dried form. The seeds are fried in hot ghee (clarified butter) until they pop, sputter and turn gray . Then they release a nutty and pungent flavor. They're usually fried with other fresh or dried spices like cumin, chilies and turmeric before they are added to other Indian dishes like dals, curries or vegetable dishes.