Coat the inside of the slow cooker with canola cooking spray. Place the pork tenderloins in bottom of slow cooker and sprinkle with garlic, salt and pepper evenly over the top.
Sprinkle chopped onions over pork and top that with barbecue sauce and beer. Cover and cook on Low for 8 hours.
Shred pork with a fork and stir to combine all ingredients. Serve pork filling on a whole grain bun or roll.
