Barbecue Jackfruit Sandwiches with Cabbage Slaw

Name: Barbecue Jackfruit Sandwiches with Cabbage Slaw
Ingredients: 2 (20-ounce) cans young green jackfruit in brine (such as Trader Joe's); 1 medium red onion; 1/2 cup, plus 1/3 cup water, divided; 1/2 cup, plus 2 1/2 teaspoons apple cider vinegar, divided; 3 ½ tablespoons dark brown sugar, divided; 2 ½ teaspoons kosher salt, divided; 2 cups shredded red cabbage (from a small cabbage); 1/3 cup chopped fresh cilantro; 1/4 cup mayonnaise; 2 large scallions, thinly sliced on an angle (about 1/3 cup); 3 teaspoons spicy brown mustard, divided; 2 tablespoons canola oil; 3 medium garlic cloves, finely chopped (1 tablespoon); 1/2 teaspoon ground cumin; 2/3 cup ketchup; 1 teaspoon chopped canned chipotle chiles in adobo sauce plus 1/2 teaspoon adobo sauce; 4 potato sandwich rolls, split and toasted; Dill pickle chips, for serving