In a small bowl, mix together the chili powder, garlic powder, Kosher salt, ground cumin, oregano and coriander
in a saucepan add the 2 tablespoons of oil over a med/low flame
slowly add in the flour whisking constantly until a roux is formed
cook the roux for about 2 mins continuing to whisk constantly
slowly add the spice mixture to the roux
slowly stream in the barbacoa broth continuing to whisk constantly until the sauce is smooth
let the sauce cook on low for about 2-3 mins and remove from the heat