Ten years ago, ponzu sauce was almost unheard of in the U.S., and there was a good reason for that. A few diners returned to our shores from Japan came with stories about how good this new taste was, but when they rushed to their local Asian market to get a bottle of the magic stuff, they were disappointed in the taste. This sad state lasted for several years until a few resourceful restaurateurs developed acceptable substitutes for the seemingly unattainable Japanese citrus, Yazu, and began producing superb Ponzu for their guests. Now the magic of Ponzu is possible in your own kitchen. Fresh is the secret; don't settle for the bottled stuff.
Zest the orange using a zester or fine grater. Juice the orange and retain 1/4 cup of juice for the ponzu sauce.
Put orange juice, zest, sake, sugar, soy sauce, lime juice and a pinch of cayenne into a saucepan.
Bring to a boil. Simmer for about three minutes to reduce the sauce by half.
Mix the water and cornstarch. Add the mixture to the simmering sauce and stir until thickened.
Allow to cook for another minute or two. Add sesame oil and stir.
Ponzu sauce is great with all kinds of fish, seafood, meats and vegetables. It's also used as a dipping sauce for appetizers and sushi.