Seeni Sambol Grilled Cheese Rolls

Place a rack in middle of oven and preheat to 325°. Toss together 3 medium shallots, finely chopped, 1 medium jalapeño, halved, seeds removed, finely chopped, 8 oz. low-moisture mozzarella, coarsely grated (about 1½ cups), 4 oz. sharp cheddar, coarsely grated (about ¾ cup), ½ cup mayonnaise, 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, and ½ tsp. crushed red pepper flakes in a large bowl to combine.

Heat 2 Tbsp. vegetable oil in a large skillet over medium-high. Cook 2 medium red onions, halved, thinly sliced, 5 fresh curry leaves (if using), 1½ tsp. Diamond Crystal or 1 tsp. Morton kosher salt, and 1 tsp. crushed red pepper flakes, stirring often and adding a splash of water if starting to burn on the bottom, until onions are softened and light golden, 9–12 minutes. Add 1 Tbsp. tamarind concentrate, reduce heat to medium-low, and cook, stirring often and adding more water if needed, until dark mahogany in color, 18–22 minutes. Remove seeni sambol from heat.

Using a long serrated knife and leaving one 12-oz. package King’s Hawaiian sweet rolls attached on the sides, slice entire slab of rolls in half through the equator. Place bottom half on a large sheet of foil and evenly dollop cheese filling over top; gently spread into an even layer. Top with seeni sambol and gently spread into an even layer. Close up sandwiches with top layer of rolls. Cover with another large sheet of foil and wrap sheets together to encase rolls.

Bake sandwiches 15 minutes. Remove top layer of foil and continue to bake until rolls are slightly browned on top, 12–15 minutes more.

If tailgating and grilling, you can assemble sandwiches in advance and follow do-ahead instructions. When ready to serve, heat a grill to low. Place foil packet on grate, cover, and grill 2–3 minutes. Turn over, re-cover, and grill 2–3 minutes. Do Ahead: Rolls can be assembled and wrapped in foil 1 day ahead. Chill.