In a small bowl stir together tomato sauce, water, chili powder, tomato paste, garlic powder, salt and cumin until blended and set aside.
Heat vegetable oil over medium heat in a small saucepan. Stir in flour until flour dissolved. Gradually whisk in tomato mixture. Reduce heat to low and stir until sauce thickens, about 4-5 minutes. Remove from heat and set aside.
For Enchiladas:
Preheat oven to 350 degrees. Lightly spray non stick cooking spray on a 9″x13″ casserole dish and set aside.
In a large bowl combine rice, black beans, corn, salsa, 1/2 cup of enchilada sauce and 1 1/2 cups of cheese. Stir until combined.
Divide mixture between each tortilla. Wrap each tortilla and place seam side down in casserole dish. Pour remaining enchilada sauce on top.
Bake for 25 minutes. Sprinkle with remaining cheese and bake for an additional 5 minutes until cheese is melted and bubbly.