01 - In a small bowl, mix salt, pepper, paprika, garlic powder, onion powder, thyme, and brown sugar. Rub the spice mixture all over the brisket, ensuring even coverage on all sides.
02 - Place the seasoned brisket in the slow cooker.
03 - In a separate bowl, combine beef broth, Worcestershire sauce, apple cider vinegar, and Dijon mustard. Pour this mixture over the brisket in the slow cooker.
04 - Cover the slow cooker and cook on low heat for 8 hours, or until the brisket is very tender and shreds easily with a fork.
05 - Transfer the cooked brisket to a cutting board. Use two forks to shred the meat, discarding any excess fat. Skim the fat from the cooking juices in the slow cooker, then return the shredded brisket to the juices to keep it moist.
06 - In a large bowl, combine the shredded green cabbage, shredded red cabbage, grated carrot, and chopped fresh parsley.
07 - In a separate small bowl, whisk together mayonnaise, apple cider vinegar, Dijon mustard, sugar, salt, and pepper until smooth and well combined.
08 - Pour the dressing over the cabbage mixture and toss thoroughly to coat all vegetables evenly. Refrigerate until ready to serve.
09 - If desired, brush the cut sides of the slider buns with melted butter and toast them lightly in a skillet or oven until golden brown.
10 - Pile the shredded brisket onto the bottom half of each bun. Top with a generous spoonful of coleslaw and add pickle slices if using. Cover with the top bun and serve immediately.