01 - Scatter the sliced onions and minced garlic evenly across the bottom of the slow cooker insert.
02 - In a small bowl, combine the smoked paprika, chili powder, ground cumin, salt, black pepper, and cayenne pepper. Rub the spice mixture generously over all surfaces of the beef chuck roast.
03 - Place the seasoned roast on top of the onion and garlic bed in the slow cooker.
04 - Pour the barbecue sauce, beef broth, apple cider vinegar, and Worcestershire sauce directly over the roast, allowing the liquids to pool around the base.
05 - Secure the lid and cook on the low setting for 8 hours. The beef is ready when it pulls apart effortlessly with gentle fork pressure.
06 - Transfer the roast to a large cutting board or platter. Using two forks, shred the meat along the grain into bite-sized strands, discarding any large pieces of fat or connective tissue.
07 - Return the shredded beef to the slow cooker and stir thoroughly to coat with the cooking liquid. Continue cooking on low for 15 to 20 minutes, allowing the meat to soak up the sauce.
08 - Pile the pulled beef generously onto burger buns and top with coleslaw, or serve over rice, in lettuce wraps, or alongside your favorite sides.