Slow-Cooker Pulled Pork Sandwiches

INGREDIENTS

• 2 teaspoons hot paprika
• 1/2 cup apple cider vinegar, plus more to taste
• 3 tablespoons light brown sugar
• Kosher salt and freshly ground pepper
• 1 3-to-4-pound boneless pork shoulder, trimmed of excess fat
• Barbecue sauce and prepared coleslaw, for serving
• 2 teaspoons vegetable oil
• 3 tablespoons tomato paste
• 1/2 teaspoon ground cumin
• 6 potato buns
• 1 teaspoon mustard powder