Kalonji seeds, also known as Nigella seeds, black cumin, or black onion seeds, are tiny, black, tear-shaped seeds from the Nigella sativa plant, prized in cooking and traditional medicine for their slightly bitter, peppery flavor and potential health benefits like antioxidant and anti-inflammatory properties. They’re used whole or ground to flavor breads, curries, vegetables, and are rich in nutrients like fatty acids, protein, and antioxidants.