Coat the tuna steaks in the sesame seeds, pressing down to coat well. Refrigerate until
Wash the rice until the water runs clear, then put in a saucepan with 500ml / 17 fl oz water.
Bring to the boil, then reduce the heat to very low and cook, covered, for 10-12 minutes. Turn off
the heat and leave, covered, for 5 minutes. While hot, pour on the combined rice wine vinegar,
mirin, sugar and 1/4 teaspoon salt. Stir with a fork to separate the grains, then fold in the
shredded nori. Keep warm.
Lightly spray the oil in a large frying pan, add the tuna steaks and cook for 1-2 minutes on
each side, or until the sesame seeds are crisp and golden. The tuna should still be a little pink
in the middle. Drain on paper towels.
Spoon the rice into four lightly greased 125ml / 4 fl oz ramekins or cups, pressing down
lightly, then invert onto each plate and remove the ramekins. Combine the mayonnaise and wasabi in
a small bowl. Serve the tuna with the nori rice and with some wasabi mayonnaise on the side.
Garnish with pickled ginger, if desired.