Step 1

Lightly coat the bottom of the slow cooker crock with cooking spray. Cut the onion into thick wedges and add to the slow cooker, then lay the ribs on top.

Step 2

In a small bowl, combine the chili powder, black pepper, salt, cumin, oregano, and garlic powder. Sprinkle the spice mixture evenly over the ribs.

Step 3

Whisk the liquid smoke into 1 cup of the barbecue sauce and pour over the other ingredients in the slow cooker.

Step 4

Cover with the lid and cook on LOW for 7 to 8 hours (HIGH 4 to 5 hours), until the ribs are tender, but not quite falling apart.

Step 5

Once the ribs are done, preheat the broiler. Transfer the ribs to a rimmed baking sheet lined with aluminum foil and discard the cooking liquid.

Step 6

Baste the remaining barbecue sauce over the ribs, then broil for about 5 minutes, watching carefully, until the ribs are caramelized.