Chill the filet mignon in the freezer for 1 to 2 hours, stopping when it is firm but still yields slightly when pressed. The beef should feel dense and semi-firm, not frozen solid.

Sharpen a long, very sharp knife, then cut the tenderloin across the grain into slices about ¼ to ⅛ inch thick. Use one smooth forward stroke per cut rather than sawing, which can tear the fibers.

Sandwich each slice between two sheets of plastic wrap or parchment paper and flatten it with the smooth side of a meat mallet. Tap gently until the beef spreads into a very thin round with a translucent sheen.

Peel back one sheet, support the beef with your palm, and lay it onto a chilled serving plate before removing the second sheet. Handle each round lightly so it stays intact and smooth.

Continue until the beef covers two dinner plates or one extra-large platter, overlapping the slices slightly where needed. A mostly even layer gives each serving the same tender texture.

Drizzle the beef with extra virgin olive oil, add a light squeeze of lemon juice, and season with flaky sea salt and freshly cracked black pepper. The surface should glisten without sitting in a pool of dressing.

Use a vegetable peeler to shave long pieces of Parmigiano Reggiano or Grana Padano over the beef. The cheese should fall in loose curls rather than thick, heavy strips.

Toss the arugula with 1 tablespoon lemon juice, 1 tablespoon olive oil, salt, and pepper, then scatter it over the beef and serve immediately. The greens should stay crisp and smell peppery as the dressing coats them.