Whisk together soy sauce, fish sauce, lime juice, honey, crushed red pepper, garlic and ginger in a small bowl. Place flank steak in a ziplock bag and add marinade. Turn bag several times to coat. Let stand for 15 minutes at room temperature, turning once or twice.
While steak is marinating, preheat broiler. Broil steak until cooked to desired doneness, about 4 minutes per side for medium-rare. Transfer to a cutting board, tent with foil and let stand for 5 minutes. Slice, transfer to a platter, pour any juices from cutting board over sliced meat and serve.