Oyster sauce is a thick, dark sauce made from oysters, soy sauce, sugar, and other seasonings. It has a savory and slightly sweet taste, with a rich umami flavor. Oyster sauce is commonly used in Chinese and Southeast Asian cuisine as a condiment or a flavoring agent. It is often used to add depth of flavor to stir-fries, noodle dishes, and vegetable dishes. The sauce is also used as a marinade for meats, poultry, and seafood. Its versatility and unique flavor make it a popular ingredient in many dishes, and it is often used as a substitute for soy sauce or salt in cooking.