The Yuzu (Citrus ichangensis x C. reticulata) is a citrus fruit 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 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).
Yuzu is unusual among citrus fruits in being relatively frost-hardy, due to its cold-hardy C. ichangensis ancestry, and can be grown in regions with winters as low as -5C where more sensitive citrus would not thrive.
The Yuzu's flavor is tart, closely resembling that of the grapefruit, with overtones of Mandarin Orange. It is rarely eaten as a fruit, though its aromatic zest (outer rind) is used to garnish some dishes, and its juice is commonly used as a seasoning, somewhat like the way the lemon is used in other cuisines. Yuzu may be used to make marmalade or as an ingredient in cakes. It is also used to make liquor and wine.
Yuzu is also known for its characteristically strong aroma, and the oil from its skin is marketed as a fragrance.