01 - Set oven to 300°F for braising
02 - Combine kosher salt, black pepper, smoked paprika, garlic powder, onion powder, and brown sugar in a small bowl. Rub the spice mixture evenly over all surfaces of the beef chuck roast.
03 - Heat olive oil in a large Dutch oven over medium-high heat. Sear the seasoned beef on all sides until deeply browned, approximately 8 minutes total.
04 - Remove the beef and set aside on a plate. Add the chopped onions and smashed garlic to the pot; sauté for 2 to 3 minutes until fragrant and softened.
05 - Return the beef to the Dutch oven. Pour in the beef broth, barbecue sauce, Worcestershire sauce, and apple cider vinegar. Bring the liquid to a gentle simmer.
06 - Cover the Dutch oven with a tight-fitting lid and transfer to the preheated oven. Braise for 3 hours, or until the beef is fork-tender and easily shreds.
07 - Remove the beef from the cooking liquid. Use two forks to shred the meat into bite-sized pieces. Skim excess fat from the braising liquid, then return the shredded beef to the pot and toss thoroughly to coat.
08 - Increase oven temperature to 350°F. Slice the slider buns in half horizontally and brush the cut sides with melted butter. Place on a baking sheet and toast for 5 to 7 minutes until lightly golden.
09 - Pile the prepared pulled beef generously onto the bottom bun halves. Top each with dill pickle slices and thin red onion slices. Cover with the bun tops.
10 - Arrange sliders on a serving platter and serve immediately while warm.