The most popular sweet and sour dish in Japan is subuta, sweet and sour pork. If you like fish, serving fried fish with sweet and sour sauce is good too.

Sweet and Sour Fish Recipe

Japanese-style Sweet and Sour Dishes

Sweet and Sour Omelet.
_{Sweet and Sour Fish Photo © 2008 Setsuko Yoshizuka, licensed to About.com, Inc.}