Wrap the beef tightly in plastic wrap and place in the freezer until very firm and almost frozen, about 1 hour. Slice as thinly as possible with a very sharp knife. The slices should be almost transparent, so flatten them by pounding them gently if you aren't able to slice them thinly enough.
Arrange the slices on serving plates and drizzle lightly with olive oil. Season with salt and pepper and add capers, chopped onion, or Parmesan curls if desired. Serve with lemon wedges. Serves 4 to 6.
Reproduced by permission of Worldwide Recipes.