Find the freshest ahi, also known as yellowfin, tuna steaks. Rub with olive oil, and wrap in a large piece of plastic, as shown. Use a rolling pin, or maybe a baseball bat, to gradually flatten the fish to a very thin layer. To serve, drizzle with olive oil; sprinkle with sea salt, black pepper, and lemon zest; and grate or peel with a potato peeler a hard cheese (mon petit ami used Manchego) on top. Garnish with some greens (such as baby arugula). Anchovies are also a nice addition.
Truc (Tip): You can make beef carpaccio exactly the same way; find fresh filet mignon to pound. Parmigiano-Reggiano is better with beef.