As far as I know, there is not, since oyster sauce contains Extract of Oyster.

OUKosher note: The following OU certified companies make kosher artificial flavor oyster sauce (as listed on the OUKosher Product Search):

• Jen Mai Oyster Sauce (Industrial)
• Kosher Depot Oyster Flavor Sauce (Consumer)
• Lotus Blossom Foods Oyster Flavor Sauce (Consumer)
• Sugar Mill Oyster Sauce (Industrial)

Update: Leann Sherman from CT wrote “My Chinese recipes are rather bland, and I read that mushroom sauce is a good substitute for oyster sauce.”

Probably a combination of a very rich mushroom sauce, good quality soy sauce and a hint of MSG (if you use it) will be the closest you can get to oyster sauce. Good luck!

The words of this author reflect his/her own opinions and do not necessarily represent the official position of the Orthodox Union.