Melt butter in saucepan over medium heat.
Saute onion until soft. Add in flour to butter mixture and make a roux (Here is a great tutorial on on how to make a roux). Add chicken broth to butter mixture and stir until smooth.
Add chilies, garlic, salt and cumin and simmer for 10-15 minutes.
Serve with tortillas, smothered burritos, green chili french fries, etc...
