Yuzu
The yuzu (Citrus ichangensis × C. reticulata, formerly C. junos Siebold ex. Tanaka; Japanese ユズ, 柚, 柚子 (yuzu); 유자 (yuja) in Korean; from Chinese 柚子, yòuzi) is a citrus fruit and plant originating in East Asia. It is believed to be a hybrid of sour mandarin and Ichang papeda. The fruit looks a bit like a very small grapefruit with an uneven skin, and can be either yellow or green depending on the degree of ripeness. Yuzu fruits, which are very aromatic, typically range between 5.5 and 7.5 cm in diameter, but can be as large as a grapefruit (up to 10 cm or larger).
Read more about Yuzu.