Cooking Instructions

1. Place the steak and vinegar in a 13 x 9-inch glass or ceramic pan. Turn to coat evenly. Cover with plastic wrap and refrigerate, turning occasionally, for at least 1 hour.
2. Prepare a charcoal or gas grill. Remove the steak from the marinade. Pour the marinade into a glass measuring cup; set aside.
3. Grill the steak directly over the heat source for about 8 minutes per side, or until the internal temperature registers 145° F on an instant-reading thermometer.
4. Remove and set aside on a cutting board with a well to catch the juices. Allow to rest for 5 minutes.
5. Meanwhile, place the spinach on dinner plates or a large platter. Microwave the reserved marinade for 2 minutes, or until boiling. Remove and allow to cool.
6. Cut the steak into thin diagonal slices. Arrange over the spinach. Drizzle with the collected meat juices. Season to taste with salt and pepper. Drizzle with oil. Cut shavings from the Parmesan cheese and scatter over the top. Pass the reserved marinade at the table. Serve the bread on the side.

Note: The flank steak may be broiled on a pan set 6 inches below the heat source for about 8 minutes each side.