Melt the butter in a pan and stir in the flour, cook for 1 minute on the stovetop. Whisk in the broth and simmer for 2 minutes.
Whisk the tomato sauce and tomato paste into the sauce. Stir in the chili powder, cumin, garlic powder, onion powder, oregano, paprika and salt.
Simmer for 5 minutes, then remove from the heat and stir in the vinegar.
Pour the sauce over the meatballs and cover with a lid. Set on low for 2-4 hours if using frozen meatballs, or 4 to 5 hours if using raw meatballs or 6-8 hours on low.
Sprinkle with the cheese and cook for another 30 minutes until the cheese is melted.
Serve with your favorite toppings.
Notes
Leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days. To reheat, simply warm them up in the microwave or on the stovetop until heated through. You may need to add a splash of water or extra enchilada sauce to prevent them from drying out.
Yes, you can prepare the meatballs and red enchilada sauce ahead of time and store it in the refrigerator until you're ready to cook. You can also assemble the meatballs and sauce and freeze them before cooking, then thaw and cook them in the slow cooker when needed. Additionally, you can make the entire dish ahead of time and reheat it before serving, making it a convenient option for busy weeknights or entertaining.