The name says its all! Sweet-and-sour sauce can sometimes be called duck sauce. They are pretty interchangeable and can be found in the supermarket ethnic aisle. Taste may differ by brand, so if you like the sauce on the sweet side, you can add 1 to 2 tablespoons of brown sugar to it. If you like it spicy, you might want to add 2 to 3 dashes of hot pepper sauce.