Press the tuna

• Place the tuna steak between two sheets of baking paper or plastic wrap.
• Press it firmly in the tortilla press until it is thin and even.
• Chill the pressed tuna so it firms up and slices cleanly.

Slice the carpaccio

• Slice the pressed tuna as thinly as possible with a sharp knife.
• Arrange the slices in a single layer on a chilled plate.

Dress and serve

• Drizzle generously with the grassy olive oil.
• Squeeze over the lemon juice and season with flaky salt.
• Serve immediately, while still cold.