01 - Arrange the sliced onions and minced garlic evenly across the bottom of the slow cooker.
02 - Combine the smoked paprika, chili powder, ground cumin, salt, black pepper, and cayenne pepper in a small bowl. Rub the spice mixture thoroughly over all surfaces of the beef chuck roast.
03 - Place the seasoned roast on top of the onions and garlic in the slow cooker.
04 - Pour the barbecue sauce, beef broth, apple cider vinegar, and Worcestershire sauce evenly over the beef.
05 - Cover the slow cooker and cook on the low setting for 8 hours, or until the beef is fork-tender and pulls apart effortlessly.
06 - Transfer the roast to a large cutting board. Using two forks, shred the beef into strands, discarding any large pieces of fat or gristle.
07 - Return the shredded beef to the slow cooker and stir to coat evenly with the sauce. Continue cooking on low for 15 to 20 minutes to reheat and allow the meat to absorb the sauce.
08 - Pile the pulled beef onto burger buns and top with coleslaw, or serve over rice or in lettuce wraps for a lighter option.