Massaging this sweet and spicy teriyaki marinade into flank steak for just five minutes is all you need to get maximum flavor. Grill summer peaches along with the meat and serve as a sweet, juicy accompaniment.
Mix marinade, ketchup, sesame seed and red pepper in small bowl. Reserve 2 tablespoons marinade for brushing.
Place steak in large resealable plastic bag. Add remaining marinade mixture; turn to coat well. Massage steak and marinade for 5 minutes. Remove steak from marinade. Discard any remaining marinade.
Grill steak over medium-high heat 7 to 8 minutes per side or until desired doneness, brushing with reserved marinade mixture. Discard any remaining marinade. Grill peach slices 1 to 2 minutes per side or until lightly browned. Cut steak across the grain into thin slices. Serve with grilled peaches.