Mustard seeds are tiny, dark seeds from an Indian mustard plant. They are usually used in tempering, or "vaghaar," which is mixing spices in hot oil. Their sharp flavor and aroma comes alive when they crackle in hot oil. This is usually added to dishes as their final seasoning. In Bengali cooking, raw mustard seeds are used to make a paste with water, chilies and ginger. This flavors their bitter vegetable stews, soups, dals and fish cuisines. Mustard also promotes healthy skin and stimulates the appetite. B. nigra.