This is an authentic enchilada sauce that takes a bit of time, but it’s well worth the trouble! You can get dried chilis in a wide variety from a specialty food or import grocery store.
5 dried poblano peppers
5 dried Anaheim peppers
2 or 3 small hot chilis (or to taste)
1 medium onion, minced
3 cloves garlic, minced
Flour or arrow-root powder
2 tsp. cumin
1/4 tsp. cinnamon
First, remove the stems and seeds from the chilis. You don’t have to get all of the seeds out, but take out the majority to keep the spice level in check and reduce bitterness in the sauce.
Reconstitute the chilies in warm water until they are soft, about 40 minutes. Put the rehydrated chillies and a little of the soaking water in a blender or food processor and process until smooth.
Cook the minced onion and/or garlic in a little oil, add some flour or a dash of arrow root powder to make a roux. Cook until smooth and bubbly. Pour in the blended chillies. Add some salt, cumin, and a tiny bit of cinnamon. Simmer until the sauce is the consistency you like, adding more of the soaking water if necessary.
This will keep in a sealed jar in the fridge for at least a week.