A wedge of Parmesan cheese to shave over the steak
Arugula or radicchio and lemon wedges
On a rimmed baking sheet, lay out the flank steak and season both sides with salt. Crush the black peppercorns and press them into the meat. Then strip the leaves from the rosemary sprigs and press those into the meat, along with the garlic slices.
Drizzle with olive oil and let sit at room temperature for about an hour. You can also marinate, covered, in the refrigerator, but be sure to bring the meat to room temperature before cooking.
Preheat your oven to 450 and place a cast iron skillet or grill pan in the oven for at least a half hour.
Carefully remove the pan from the oven and lay the flank steak in the pan and close the oven door. After about 5 minutes, flip the steak (it should be nicely caramelized on the bottom) and cook another 3 or 4 minutes for medium rare.
You can also cook the meat on your charcoal or gas grill, but be careful with flare-ups because of the olive oil on the surface of the meat.
Cut thin slices of meat on the diagonal and against the grain. Arrange the slices on a platter lined with the arugula or radicchio and garnish with the lemon wedges.
With a vegetable peeler, shave slices of Parmesan over the meat and drizzle with additional olive oil.