Wrap the tuna in paper towel and refrigerate for 4 hours.
Remove the tuna from the fridge and discard the paper towel. Rewrap the tuna in plastic wrap and place in the freezer for 4–5 hours until frozen.
Cut 24 sheets of non-stick baking paper a little bigger than the tuna block and set aside.
Remove the tuna from the freezer and unwrap. Place the fish on a slicing machi