Tartare sauce (also known as tartar sauce) is a thick white sauce made from mayonnaise and finely chopped vegetables (usually including pickled gherkins, capers and pickled onions ) which is frequently used to season fish and chips and other fried fish dishes. It can also be made simply by mixing commercially produced relish and mayonnaise.

Not to be confused with cream of tartar.

Tartar sauce is also a phrase used in SpongeBob SquarePants usually said when something bad has happened or is about to happen.