Into a medium saucepan over medium heat, add the vegetable oil. When the oil is hot, stir in the all-purpose flour and chili powder. Cook, stirring frequently, for about 3 minutes, until slightly darkened.
Add tomato sauce, water, sea salt, ground cumin, garlic powder, and onion powder. Stir to combine.
Continue cooking, stirring frequently, for 10 minutes. Sauce will thicken slightly.
Adjust seasoning to taste. The sauce is now ready for use in any recipe that calls for red enchilada sauce.