Hot chili oil is an Asian condiment made with dried hot chile steeped in oil with some additional flavorings like garlic and ginger. This oil is used widely in Chinese and other Asian cooking. You will frequently see this hot oil sitting on the table in most Chinese restaurants.
This oil is frequently used in dipping sauces but it can be added any dish where you want to add some heat and flavor. I liked to drizzle over hot rice. You can add it to your favorite sesame dressing recipe or add it to a marinade for chicken or pork.
This is a really common condiment and you'll probably finding in the "ethnic foods" section of most any well stocked grocery store. Of course you can always find it online at Amazon.com. Look for Dynasty brand which is pretty good.
If you ran out of hot chili oil or just don't have it and don't want to buy it you can use one of these substitutes.
1 cup peanut or corn oil
12 - 3" long red, dried hot chiles like de arbol or Thai chiles