1. Prepare the Ribs: Remove any excess fat from the ribs. If the ribs are large, cut them into sections that will fit into your slow cooker.

2. Season the Ribs: In a small bowl, mix together the smoked paprika, ground cumin, black pepper, salt, and red pepper flakes (if using). Rub this seasoning mix all over the ribs.

3. Prepare the Slow Cooker: Place the chopped onion and minced garlic at the bottom of the slow cooker.

4. Add the Ribs: Arrange the seasoned ribs on top of the onions and garlic.

5. Mix the Sauce: In a separate bowl, combine the barbecue sauce, beef broth, and brown sugar. Pour this mixture over the ribs in the slow cooker.

6. Cook: Cover the slow cooker and cook on low for 6-8 hours, or until the ribs are tender and falling off the bone.

7. Finish: Once cooked, you can optionally transfer the ribs to a baking sheet and broil them in the oven for a few minutes to caramelize the sauce, if desired.

8. Serve: Serve the ribs with extra barbecue sauce on the side and enjoy!

Feel free to adjust the seasonings and sauce according to your taste.