Which ingredient is prominently used in the preparation of Panda Express's Sweet and Sour Sauce?

The prominent use of pineapple juice in Panda Express's Sweet and Sour Sauce is key to its distinctive flavor profile. Pineapple juice contributes not only sweetness but also a tangy acidity that balances the richness of fried foods or stir-fried dishes. This combination of sweet and sour is a hallmark of desserts and sauces that aim to provide a burst of flavor.

While soy sauce is a common component in many Asian sauces, it primarily lends a salty umami flavor, which is not the main characteristic of Sweet and Sour Sauce. Similarly, sesame oil is often used for its nutty flavor in other dishes but does not play a significant role in this particular sauce. Teriyaki sauce, which is known for its sweetness and savory notes, is a different style altogether, typically blending soy sauce, sake, and sweeteners, thus not aligning with the expected profile of Sweet and Sour Sauce.