- Heat a large griddle pan. Brush each tuna steak with the oil, season generously with the black pepper to taste. Set aside
- Mix the wasabi, vinegar and mirin together. Arrange the cucumber slices on a tray and spoon the dressing over the top. Leave to ‘cure’ for 30 minutes.
- Heat a griddle pan until very hot. Add the seasoned tuna steaks and griddle for 2 minutes on each side – less if you like your tuna rare.
- Drain the cucumber and toss into the watercress with the sushi ginger. Pile onto a serving dish and arrange the lime wedges around the edge and sprinkle the sesame seeds over the top.
- Arrange the cooked tuna around the salad and take to the table to serve.