In a small saucepan, mix flour (or potato starch) and chili powder together. Add oil, and mix to combine. Heat on low for 2 minutes, or until fragrant.
Turn the heat up to medium, add broth, tomato paste, oregano, and cumin, stirring to combine. Bring to a boil, reduce heat to low and cook, covered, for 10 minutes, until sauce thickens and smooths out. Add salt and sugar, and taste for seasonings, adjusting to taste.
Makes about 2 cups, or 1 pint of sauce For the servings, I figured about 1/4 cup per serving, though this may change depending on how you're using the sauce.