1. Heat 1 Tbsp. oil over low to medium heat in a large saucepan.
2. Stir in flour. Brown to make a roux, stirring constantly.
3. Stir in chile powder.
4. Add warm water to make a sauce of the thickness you desire.
5. Add garlic, salt and oregano. Simmer for at least 30 minutes while flavors blend.
6. To assemble the enchiladas, quickly dip corn tortillas one at a time in hot oil to soften. Drain on paper towels.
7. Dip each fried tortilla in chile sauce to cover bottom of a casserole dish. Spread a large serving spoonful of chile sauce over tortillas, enough to cover all tortillas. Sprinkle with onion and cheese. Add remaining layers of fried tortillas dipped in chile sauce, onion and cheese until all ingredients are used. Add remaining sauce on top or pour over individual servings.
8. Bake at 350 for 20 minutes or until cheese on top is melted.