Soy sauce is a readily available substitute for oyster sauce in cooking. There are also vegetarian oyster sauce alternatives made using 100 percent vegetable products that mimic the flavor of the traditionally fermented oyster sauce.
Because of the similar taste profile to mushrooms, a soy sauce with mushrooms or a mushroom sauce are also great substitutes for oyster sauce. The thick, viscous oyster sauce is commonly used in Asian cooking to lend saltiness as well as a unique flavor to a variety of stir-fried dishes. However, because its main role is to add saltiness, any of these substitutions can seamlessly be used with good results.