Make the enchilada sauce first. Heat the oil in a saucepan over medium heat. Whisk in the flour to make a roux. Continue stirring for about 1 minute. Add in the rest of the ingredients. Bring to a boil and then reduce heat to a simmer until ready for use.
Preheat oven to 400 degrees. Heat oil in skillet. Add the beef, chili powder, oregano, cumin, salt, onion and bell pepper. Saute until meat is slightly brown and vegetables are translucent about 5-6 minutes.
Place mixture in mixing bowl and add 1 cup of the cheese and 1 cup of the sauce. Stir until fully incorporated.
Spray a 9 x 13 baking dish with cooking spray. Spoon the beef filling into the middle of the tortilla. Fold each side of the tortilla towards the middle and place seam side down into the dish. Repeat with the remaining tortillas.
Pour the remaining enchilada sauce and cheese over the filled tortillas. Bake for about 15 minutes.
*For less spice you can substitute the cheese with monterey jack cheese