01 - Arrange 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 thoroughly over all surfaces of the beef chuck roast.
03 - Set the seasoned beef chuck roast directly 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 evenly over the roast, allowing the liquids to pool around the base.
05 - Secure the lid and cook on the low setting for 8 hours, or until the beef is fork-tender and pulls apart with minimal effort.
06 - Carefully remove the roast from the slow cooker and transfer to a large cutting board. Using two forks, shred the beef into bite-sized pieces, 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 an additional 15–20 minutes, allowing the meat to reheat and soak up the flavors.
08 - Pile the pulled beef generously onto burger buns and top with coleslaw, or serve over rice or in lettuce wraps for a lighter option.