01 - Pat the beef roast dry with paper towels and season all sides generously with kosher salt and black pepper.
02 - Arrange the sliced yellow onion and minced garlic cloves evenly across the bottom of the slow cooker insert.
03 - Place the seasoned chuck roast on top of the onion and garlic bed, ensuring the meat sits flat.
04 - In a medium bowl, whisk together beef broth, barbecue sauce, Worcestershire sauce, apple cider vinegar, brown sugar, smoked paprika, and chili powder until fully incorporated.
05 - Pour the prepared sauce mixture evenly over the beef roast, ensuring some sauce reaches the onions at the bottom.
06 - Cover and cook on LOW setting for 8 hours (or HIGH for 4–5 hours) until the beef is fork-tender and easily shreds apart.
07 - Transfer the cooked beef to a large bowl and shred using two forks, removing and discarding any large pieces of excess fat.
08 - Skim any excess fat from the cooking liquid remaining in the slow cooker, then return the shredded beef and toss thoroughly with the juices.
09 - Pile the saucy pulled beef onto sandwich buns and top with coleslaw, pickles, or additional barbecue sauce as desired.