In a large skillet cook beef and onion over medium heat for 6-8 minutes or until no longer pink.
Stir in flour and seasonings. Stir in tomatoes; bring to a boil. Reduce heat and simmer for 15 minutes.
Preheat oven to 350. In a medium saucepan, heat butter over medium high heat. Add garlic. Cook and stir 1 minute or until tender. Stir in flour until blended. Gradually whisk in the broth. Bring sauce to a boil and stir about 2 minutes until thickened.
Pour 1 1/2 cups sauce into a 9x13 in baking dish. Assemble the enchiladas by putting 1/4 cup beef mixture off center of each tortilla. Top with 1-2 Tbs cheese and roll up. Place seam side down into 9x13.
Bake covered 30-35 minutes or until heated through. Remove foil and top with remaining cheese baking an additional 10-15 minutes.
If you are making this in a crockpot with beef stew meat, add all ingredients including sauce ingredients except for the flour. Stir in the flour at the end of cooking and allow to thicken. Cook on low 4-6 hours.