You can buy chili oil in Asian markets or in the ethnic foods section of the supermarket. You can also substitute with olive oil and a pinch of red chili flakes or use recipe #175117. Most of the recipe can be made in advance, and you can quickly finish the beans at the last minute. This is from Firehouse Food: Cooking with San Francisco's Firefighters. Edit: You may want to start with 1 tablespoon of chili oil and adjust to your liking.