Heat the fat in a sauce pan over a medium low heat. Once hot add the flour and stir to combine. Cook for 2 minutes stirring constantly. (This is your roux.)
Add the red chile powder and stir for no more than 30 seconds. The mixture will be quite clumpy. (Don't go past 30 seconds because chile powder can burn easily if the pan is too hot or you cook it too long without liquid.)
Slowly add the liquid, whisking to break up the clumps. Keep whisking until you have a smooth sauce.
Add the remaining ingredients (except for the sugar).
Simmer for about 15 minutes, stirring frequently until the sauce thickens. If the sauce gets too thick, add a little more liquid - 1 Tbsp. at a time - to get the consistency you want.
Taste. If the sauce is too hot or bitter, add a little bit of sugar.
If you could let the sauce rest overnight in the refrigerator, that would be best. It would allow the chile powder to rehydrate for a smoother texture and the flavors to meld.
