Recipe and photo courtesy of the Wisconsin Beef Council.
Balsamic Marinated Flank Steak
In a small bowl, combine vinegar, olive oil, basil leaves, mustard, garlic, and sugar to make marinade.
Place beef flank steak and marinade in a food-safe plastic bag; turn steak to coat.
Close bag securely and marinate in refrigerator for 6–12 hours, turning occasionally.
Remove steak from marinade; discard marinade. Preheat grill to medium heat.
Grill steak for 16–21 minutes, to desired doneness (130–135 degrees for medium rare and 140–145 degrees for medium doneness), turning occasionally.
Season steak with salt and pepper, as desired.
Carve steak crosswise into thin slices.