Which of the following condiments is essential for making stir-fry dishes?

Oyster sauce is essential for making stir-fry dishes due to its unique flavor profile, which enhances the overall taste of the meal. It is a savory and slightly sweet sauce made from oyster extracts, sugar, salt, and other seasonings. When incorporated into stir-fry, it provides umami and depth, contributing to the rich flavor typically sought in these dishes.

In contrast, while Sriracha can add heat and spice, and ketchup offers sweetness, neither brings the necessary depth of flavor that oyster sauce does. Mustard, on the other hand, is not commonly used in Asian stir-fry cuisines and would not complement the other ingredients in the same way oyster sauce can. Thus, oyster sauce stands out as a crucial element for achieving the authentic taste associated with stir-fry dishes.