A distinctive Japanese topping is grated daikon (large, sweet radish) with a dash of soy sauce. It's usually served with broiled fish, the radish adding a tangy sharpness and the soy sauce filling out the subtle flavor of the fish. When used as a topping for hamburgers, you can also sprinkle some lemon juice for extra flavor.
Grated daikon prevents soy sauce from running when poured on a meat or fish dish and softens the sauce's saltiness. It's also a refreshing alternative to rich, creamy toppings.