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 thoroughly with the spice mixture.
03 - Heat olive oil in a large Dutch oven over medium-high heat. Sear the seasoned brisket for 3-4 minutes per side until deeply browned.
04 - Transfer the brisket to a plate. Pour beef broth, apple cider vinegar, and Worcestershire sauce into the pot, scraping up the browned bits from the bottom. Return the brisket to the pot with the fat side facing up.
05 - Cover the Dutch oven tightly with its lid. Roast in the preheated oven for 4 to 4.5 hours until the meat pulls apart easily with a fork.
06 - Remove the cooked brisket to a cutting board and allow it to rest for 10 minutes. Shred the meat using two forks. Skim any excess fat from the braising liquid and discard.
07 - Combine the shredded brisket with 1/2 cup of barbecue sauce and a few spoonfuls of the reserved cooking liquid for moisture.
08 - Switch the oven to broil. Arrange slider buns cut-side up on a baking sheet, brush with melted butter, and broil for 1-2 minutes until golden brown.
09 - Build each slider by layering the toasted bottom bun with sauced brisket, extra barbecue sauce, cheddar cheese, red onion slices, and coleslaw. Crown with the bun tops and serve immediately.