Black sesame seeds
Unhulled black sesame seeds, stronger and slightly more bitter than white sesame.
Black sesame is almost always available in Asian grocers, organic shops and health food stores, and only occasionally in ordinary supermarkets. It is usually toasted briefly in a dry pan until fragrant before use.
Substitute:
White sesame comes close in flavour but is milder and loses the dark colour; for pastes or desserts that depend on the black colour, there is no equivalent substitute.