Choose a piece of tuna that's about 2.5cm (1in) thick. It has the best taste and texture if it's lightly seared so it's almost raw, and still a deep pink inside, but if you like it more cooked ...
Heat the skillet over a high flame and coat it lightly with oil. When the skillet is very hot, place the tuna fillets in it and sear them one side, then flip them over and sear the other side.
Heat the pan until really hot, then cook the tuna for about 1½ minutes each side so that it’s still slightly raw in the middle, like a rare steak. Serve the tuna with generous spoonfuls of the ...