In a small mixing bowl, combine the 1 tbsp brown sugar, 1 tbsp smoked paprika, 1 ½ tsp kosher salt, 1 tsp black pepper, 1 tsp garlic powder, 1 tsp onion powder, ½ tsp cumin, and ½ tsp cayenne pepper (if using). Mix well.

Pat the 4 lb boneless pork shoulder completely dry with paper towels. This helps the rub adhere and promotes better flavor development. Rub the spice mixture all over every surface of the boneless pork shoulder, pressing it in firmly.

Place the chopped yellow onion and smashed 4 cloves garlic smashed cloves in the bottom of your slow cooker. Pour in the ½ cup apple cider vinegar, ½ cup chicken broth, and 1 tbsp Worcestershire sauce.

Set the rubbed 4 lb boneless pork shoulder on top of the yellow onion and 4 cloves garlic smashed. Spoon 1 cup of the grill sauce over the top of the boneless pork shoulder, coating it evenly.

Cover and cook on LOW for 8–10 hours or on HIGH for 5–6 hours, until the 4 lb boneless pork shoulder is completely tender and easily shreds with a fork.

Carefully transfer the 4 lb boneless pork shoulder to a large cutting board or mixing bowl. Use two forks to shred the meat, discarding any large pieces of fat. Skim excess fat off the top of the cooking liquid in the slow cooker.

Return the shredded 4 lb boneless pork shoulder to the slow cooker. Stir in the remaining ½ cup of BBQ sauce and mix well so the 4 lb boneless pork shoulder absorbs all the juices. Taste and adjust seasoning if needed. Keep warm on the LOW setting until ready to serve.

While the 4 lb boneless pork shoulder cooks, combine the shredded 3 cups green cabbage finely shredded, 1 cup red cabbage finely shredded, and grated medium carrot in a large mixing bowl.

In a small mixing bowl, whisk together the 3 tbsp mayonnaise, ½ cup apple cider vinegar, 1 tsp granulated sugar, 1 ½ tsp kosher salt, and 1 tsp black pepper until smooth. Pour the dressing over the 3 cups green cabbage finely shredded mixture and toss well to coat. Cover and refrigerate for at least 30 minutes — the coleslaw gets better as it sits.

Split the 12 pieces slider buns Hawaiian rolls or brioche slider buns preferred and lightly toast them cut-side down in a dry skillet over medium heat for 1–2 minutes until golden. This prevents the buns from getting soggy.

Pile a generous amount of pulled 4 lb boneless pork shoulder onto the bottom half of each 12 pieces slider buns Hawaiian rolls or brioche slider buns preferred. Top with a spoonful of coleslaw and a 12 slices bread-and-butter pickles slice if desired. Add an extra drizzle of grill sauce, then place the top 12 pieces slider buns Hawaiian rolls or brioche slider buns preferred on and serve immediately.