First, peel off the membrane on the back of the ribs by sliding a dull knife under the membrane and over a bone. Then, just lift and loosen the membrane until it tears. Grip the membrane and pull it off.
In a small glass bowl, mix together garlic powder, onion powder, paprika, salt, black pepper, cumin and chili powder. Sprinkle seasoning and rub it front and back of the ribs.
In a large measuring cup, pour beef broth and liquid smoke and stir well to combine. Pour the liquid inside of the slow cooker.
Place the ribs in the slow cooker and top with sliced onions.
Cover with lid and cook on low setting for 7-8 hours or high setting for 4-5 hours.
When ribs are tender and falling apart, transfer onto a baking sheet, lined with parchment paper.
Set the oven to broil (grill). Transfer the cooked ribs onto the prepared baking sheet, then brush with barbecue sauce.
Place in the oven for about 2-3 minutes. Enjoy!