Oyster sauce is a sauce made from oysters. Usually, oyster sauce refers to a viscous dark sauce popular in Southeast Asia, made from sugar, salt, oyster essence and corn starch as a thickener. Despite the fact that oyster sauce is prepared from seafood, it does not have a “fishy” taste and smell. When making the vegetarian option, mushrooms, usually oyster mushrooms or shiitake, are used instead of oysters. Oyster sauce gives the food a salty, savory taste and is actively used in Chinese, Vietnamese, Thai, Khmer and other East Asian cuisines.