01 - Preheat the oven to 300°F.
02 - Combine kosher salt, black pepper, smoked paprika, garlic powder, onion powder, cayenne pepper, and brown sugar in a small bowl. Pat the brisket dry and coat the meat evenly with the rub mixture.
03 - Heat olive oil in a large oven-safe pot or Dutch oven over medium-high heat. Sear the brisket for 3 to 4 minutes per side until deeply browned on all surfaces.
04 - Remove the brisket from the pot. Pour in beef broth, apple cider vinegar, and Worcestershire sauce, using a wooden spoon to scrape up any browned bits from the bottom. Return the brisket to the pot with the fat side facing up.
05 - Cover the pot tightly with a lid or aluminum foil. Transfer to the preheated oven and braise for 4 to 4.5 hours until the meat shreds easily with a fork.
06 - Remove the cooked brisket to a cutting board and let rest for 10 minutes. Shred the meat using two forks, pulling against the grain. Skim and discard excess fat from the braising liquid.
07 - Toss the shredded brisket with 1/2 cup of barbecue sauce and 2 to 3 tablespoons of the reserved cooking liquid to maintain moisture.
08 - Set the oven to broil. Arrange slider buns cut side up on a baking sheet, brush with melted butter, and broil for 1 to 2 minutes until golden brown.
09 - Layer the bottom buns with seasoned brisket, an extra drizzle of barbecue sauce, cheddar cheese if desired, sliced red onion, and coleslaw. Crown with the top bun halves and serve immediately.