Heat the oil in a medium saucepan over medium heat. Whisk in the flour and cook for a minute or two until it turns light brown, whisking constantly.
Add the chili powder, bouillon, garlic powder, cumin, and oregano. Whisk just until combined, then whisk in the chicken broth. Continue whisking until the mixture is smooth.
Turn the heat down to low and simmer for 10-15 minutes, or until slightly thickened, whisking occasionally.
Notes
If you prefer, you can use a tablespoon or two of tomato paste and 1/2 teaspoon of salt in place of the tomato bouillon. The sauce will be thicker, so you will only need to simmer for a couple of minutes.
Leftover sauce can be stored in an airtight container in the refrigerator for about a week, or in the freezer for 3-4 months.