Cook boneless country style ribs in the slow cooker on low for eight to nine hours. Prepare 4 to 5 pounds of ribs by trimming away any excess fat, washing the pork and patting the ribs dry before placing them in the pot.
Prepare the crock of a 5- to 6-quart slow cooker by lightly greasing it or adding a cooking liner before adding the ingredients. Cut a large onion in half and then into thin slices, and then line the bottom of the crock with the onion slices. Place the pork in the pot, and sprinkle the top with 1/2 teaspoon salt, 1/4 teaspoon ground black pepper and 1/4 cup light brown sugar. Mince 2 garlic cloves and add to the crock along with 1/2 cup of apple juice. Place the lid on the pot, and turn it to low.
After the ribs have cooked, drain the liquid from the pork, and add a 16- to 18-ounce bottle of prepared barbecue sauce to the pork. Stir the ribs to distribute the sauce, put the cover back on the pot and cook on low for another hour. Serve the ribs whole, or use two forks to pull the meat apart for tender pulled pork sandwiches.