In a small bowl, mix together the brown sugar, smoked paprika, garlic powder, onion powder, salt, and black pepper.
Rub the spice mixture all over the pork ribs, ensuring they are evenly coated.
Place the sliced onions at the bottom of the slow cooker.
Lay the seasoned ribs on top of the onions.
Pour the barbecue sauce over the ribs, making sure they are well covered.
Cover and cook on low for 6–8 hours, or until the ribs are tender and falling off the bone.
Carefully remove the ribs from the slow cooker and place them on a baking sheet.
Preheat the oven’s broiler.
Brush additional barbecue sauce over the ribs and broil for 3–5 minutes, or until the sauce is caramelized.
Serve hot, garnished with the caramelized onions from the slow cooker.
Variations & Tips
For a spicier kick, add a teaspoon of cayenne pepper to the spice rub.
For a sweeter glaze, mix in a tablespoon of honey or maple syrup with the barbecue sauce.
Add a few drops of liquid smoke for extra smoky flavor.
Serve the sauce on the side if you have picky eaters.