Turn the rib bone side up, and use a small knife to scrape off an edge of the membrane. Peel it off slowly until it is all removed. Cut the ribs in half (if it is too long to fit in the slow cooker as it is).
Stir together all the seasoning. Rub mixture all over the top and sides. Then brush about half of the BBQ sauce over the ribs.*
Place the rib in the slow cooker. Add chopped onion, garlic and 1/4 cup of water or stock.
Cover and cook on low for 7.5 - 8 hours.
Preheat the oven to high broil. Gently take the ribs out of the slow cooker and place on a parchment paper-lined baking pan. Brush the rest of the BBQ sauce on top and all the sides (or reserve some for dipping later). Broil for 4 -5 minutes to charr.
Notes
* For best result, let the rib marinate in the dry rub overnight.
Increase/decrease the ratio of the seasoning depending on the amount of ribs you are working with or your preference to taste.
Note: Nutrition Facts below may vary depending on the BBQ sauce you choose to use.