Drain pineapple, reserving juice and 1/2 cup pineapple (save remaining pineapple for another use). In a large bowl, combine reserved crushed pineapple, pepper and salt. Crumble beef over mixture and mix well. Shape into 4 patties; place in a 13x9-inch glass baking dish.
In a small bowl, combine soy sauce, ketchup, vinegar, garlic, pepper flakes and reserved pineapple juice. Pour marinade into dish; cover and refrigerate 1 hour, turning once.
Drain and discard marinade. Pan-fry patties over medium heat until a thermometer reads 160Â° and juices run clear.
Serve burgers on buns with tomato and jalapeno peppers if desired.