A yuzu (Citrus aurantium, formerly C. junos; Japanese) is a citrus fruit that grows in Japan. It looks a bit like a small grapefruit, and can be either yellow or green.
Yuzu flavor closely resembles that of the grapefruit, with overtones of Mandarin orange but it is rarely eaten as a fruit. It is commonly used as a herb somewhat like the way a lemon is used in other cuisines. Its outer skin is also used to garnish a dish. Yuzu may also be used to make marmalade or a cake. Yuzukosho, lit. yuzu and pepper, is a hot and spicy sauce made with green yuzu skin and green pepper.