Combine soy sauce, honey, vinegar, ginger, garlic powder and vegetable oil in a small bowl. Mix well. Lay steak in a shallow glass or ceramic dish. Pierce flesh all over front and back with a sharp fork. Pour marinade over steak, then turn and coat the other side. Cover, and chill in the refrigerator 8 hours, or overnight. Preheat an outdoor grill for high heat. Place grate on highest level, and brush lightly with oil. Grill steak for 15 to 20 minutes, turning once, to desired doneness.