Teriyaki Pork and Beef Burger

Name: Teriyaki Pork and Beef Burger
Ingredients: 1 pound ground beef sirloin; 1 pound ground pork; 1/2 medium yellow onion, grated on the large holes of a box grater; 2 tablespoons minced fresh garlic; Kosher salt and freshly ground black pepper; 2 tablespoons unsalted butter; 1/4 cup firmly-packed light brown sugar; 1 ripe pineapple, peeled, quartered, cored and cut into 1/4-inch dice; 1 dragon fruit, peeled and cut into 1/4-inch dice; 1 bunch fresh cilantro, minced; 1/4 cup soy sauce; 2 tablespoons minced fresh ginger; 6 hamburger buns