Made from toasted sesame seeds, the rich flavor of Chinese sesame paste lends flavor to many Szechuan dishes. Sesame paste is sold in jars in Asian markets; Lian How is a good brand. However, if you're looking for a quick sesame paste substitute, try mixing 4 teaspoons peanut butter with 1/2 teaspoon Asian sesame oil. Make sure to use Asian sesame oil (also made from toasted sesame seeds), which can be found in the ethnic or international section of many supermarkets.