Add the oil to a pan over medium heat. When the oil is hot, stir in the flour and chili powder. Use a whisk (this will help prevent lumps in your sauce) to stir constantly under it starts to brown (a minute or two)
Continue to stir as you add the remaining ingredients. Cook until sauce begins to thicken – about 10 minutes. If you are wanting to speed things up you can bring the sauce to a boil for a minute or two and the sauce will thicken a bit quicker.
Recipe by Talking in ALL CAPS at https://talkinginallcaps.com/2011/05/bbq-chicken-enchiladas.html