The Yuzu is a unique citrus hybrid native to China and Tibet. It is widely used in Japan but is rare and highly sought after in the United States. The fruit is small to medium size with a rough, aromatic rind and has many, large seeds. It is usually used green or as it is just beginning to turn yellow. Yuzu juice is strongly acid but like the rind, has unique, piney-citrus flavor.
Japanese chefs us both the juice and the rind of Yuzu. The juice is often used to make Ponzu sauce, a citrus-soy combination that can also include bonita flakes (dried tuna). Here's a traditional recipe is described in Asian Grilling by Su-Mei Yu (William Morrow):
Ponzu Sauce
3 tablespoons mirin (sweet rice wine)
2 tablespoons rice vinegar
1 tablespoon soy sauce
2 tablespoons bonito flakes
1/4 cup fresh yuzu juice, or more to taste
Combine the mirin, vinegar, soy sauce, and bonito flakes in a saucepan and bring to a boil over medium heat. Remove from the heat and let cool.
Pour the sauce through a strainer into a bowl; discard the bonito flakes. Add the yuzu juice. Serve, or store in a glass jar with a tight-fitting lid in the refrigerator for up to 3 days. Add more yuzu juice if needed before serving.
This sauce complements traditional Japanese grilled fish, chicken or shrimp dishes. It is also excellent with shushi..
Yuzus are becoming a common ingredient in many of the most progressive restaurants, including Nobu's in New York and Spago in Los Angeles. At Spago, Yuzu rind is used to flavor kocho, a starchy bread-like staple, served with a Gratin of Wild Japanese Matsutake Mushrooms. Yuzu is also used to flavor miso soups, salad dressings and even ice cream. The aromatic star is also prized for cosmetics and bath, fragrance and beauty products.