Confusingly, 'black lentils' can mean two different legumes. True black lentils, also marketed as beluga lentils for their resemblance to caviar, are a small, shiny, disk-shaped variety of the common lentil (Lens culinaris); they hold their shape well when cooked and have a firm, slightly nutty bite, which makes them popular in salads and side dishes in Western cooking. In South Asian cooking, 'black lentils' more often means whole urad dal (black gram, Vigna mungo), a different legume entirely, used in the classic North Indian dish dal makhani and, once split and hulled, in dosa and idli batters. Beluga lentils cook quickly without soaking, while whole urad dal needs a long soak and simmer; the two aren't interchangeable, since urad dal has a starchier, slightly slippery texture while beluga lentils stay firm and separate.