- 3T + 1/4t white flour
- 3T vegetable oil
- 4t achiote powder
- 2c chicken broth
- 1t ground cumin
- 3t garlic powder
- 3t onion powder
- 1/2t sugar
- 1 pinch ground cinnamon (less than 1/16t)
Make a medium-dark roux. Add achiote, whisk in until mixed, then immediately add chicken broth. Stir well to mix. Add cumin, garlic, onion, sugar, and cinnamon, stirring well after each addition. Bring to a boil. Stir and cook 3 to 5 more minutes. Turn off heat.
"You will notice that as this sauce sits it will form a "skin" on the surface. This is normal and in fact the longer the sauce sits the thicker this skin becomes. All you have to do is peel the skin off and throw it away."
From: 
http://www.cooking-mexican-recipes.com/enchilada-sauce-recipe.html