In small bowl, combine honey, ketchup, vinegar, horseradish, garlic and red pepper flakes until well blended. Set aside half of sauce. In separate bowl, mix together salmon, bread crumbs, onion, green pepper and egg white. Blend in 2 tablespoons remaining sauce. Divide salmon mixture into 2 patties, 1/2 to 3/4 inch thick. Place patties on well-oiled grill, 4 to 6 inches from hot coals. Grill, turning 2 to 3 times and basting with remaining sauce, until burgers are browned and cooked through. Or place patties on lightly greased baking sheet. Broil 4 to 6 inches from heat source, turning 2 to 3 times and basting with remaining sauce, until cooked through. Place on hamburger buns and serve with reserved sauce.