Pulled Pork Sandwich with Mango BBQ sauce

Name: Pulled Pork Sandwich with Mango BBQ sauce
Ingredients: Ingredients; 1 boneless pork shoulder (Boston butt), about 3 pounds, excess fat removed; Rub:; 2 tablespoons dark brown sugar; 1 tablespoon paprika; 2 teaspoons kosher salt; BBQ Sauce:; 1/4 cup vegetable oil; 1/2 teaspoon cumin seeds; 1/2 teaspoon fennel seeds; 1 onion, finely minced; 2 tablespoons minced ginger; 1 serrano pepper, thinly sliced (seeds discarded if you don't like it spicy); Kosher salt; 2 cups mango puree; 1/2 cup fresh lime juice; 1/4 cup apple cider vinegar; 2 tablespoons molasses; 1/4 cup Worcestershire sauce; Brioche rolls, split