Remove the membrane from the underside of the pork ribs to ensure maximum tenderness. Pat the ribs dry thoroughly using paper towels.
Combine the smoked paprika, chili powder, salt, and black pepper in a small bowl. Rub this spice blend evenly across both sides of the ribs.
Cut the ribs into smaller sections if necessary, then place them in the slow cooker. Sprinkle the chopped onion and minced garlic over the top of the meat.
In a separate mixing bowl, whisk together the barbecue sauce, brown sugar, apple cider vinegar, and Worcestershire sauce. Pour the resulting mixture over the ribs in the slow cooker, ensuring they are well-coated.
Cover and cook on the LOW setting for 7 to 8 hours or on HIGH for 3 to 4 hours, until the meat is extremely tender and begins to pull away from the bone.
For a caramelized finish, transfer the cooked ribs to a baking sheet, brush generously with extra barbecue sauce, and broil in the oven for 3 to 5 minutes, watching closely to prevent burning.
Slice between the bones and serve hot, accompanied by additional barbecue sauce if desired.