Mirin
A sweet Japanese rice wine for cooking that gives sauces and marinades a mild sweetness and a light gloss.
Mirin is sold in every Asian grocery and increasingly in well-stocked supermarkets. True mirin lists rice, koji and alcohol on the label, while cheap mirin-style seasonings are based on glucose syrup.
Substitute:
Sake or dry white wine with a little sugar, about one teaspoon per tablespoon, comes close, but tastes less rounded and gives less gloss.