Barbecue Pulled Pork

Name: Barbecue Pulled Pork
Ingredients: 1/4 cup packed dark brown sugar; 1 tablespoon chili powder; 2 teaspoons ground cumin; 1 teaspoon mustard powder; 1/2 teaspoon ground allspice; 1/2 teaspoon cayenne pepper; Kosher salt and freshly ground black pepper; 4 pounds boneless pork shoulder, trimmed and cut into 4-inch pieces; 1 tablespoon vegetable oil; 1 onion, chopped; 4 cloves garlic, chopped; 1 tablespoon tomato paste; 2 cups low-sodium chicken broth; 1/2 cup ketchup; 1/4 cup apple cider vinegar; 7 hamburger buns or potato rolls; Coleslaw and pickle slices, for serving