Instant Pot Barbecue Pulled Chicken Sandwiches

Ingredients

• 1½ tablespoons cider vinegar
• 1 tablespoon mayonnaise
• 1 teaspoon packed brown sugar
• 1 teaspoon table salt
• 2 cups shredded green cabbage
• 1 Granny Smith apple, cored and cut into thin matchsticks
• 1 shallot, halved and sliced thin
• ¾ cup ketchup
• 2 tablespoons packed brown sugar
• 2 teaspoons Worcestershire sauce
• 2 teaspoons Dijon mustard
• 2 teaspoons hot sauce
• 2 tablespoons vegetable oil
• ½ cup finely chopped onion
• 2 teaspoons granulated garlic
• 2 teaspoons chili powder
• ¾ teaspoon table salt
• ½ teaspoon cayenne pepper
• 2 pounds boneless, skinless chicken thighs, trimmed
• 6 brioche hamburger buns, toasted if desired