Pour a little olive oil into a non-stick frying pan and, when hot, sear the tuna by cooking it for a couple of minutes on each side, until it’s golden brown on the outside but still red in the middle. If you don’t like your tuna rare, you can cook it for longer, but at a lower temperature to stop the outside from drying out.
For the sauce, fry the chopped onion in the extra virgin oil with a chilli pepper tip. When the onion is done, remove the chilli and add the tomato sauce, salt, sugar and black pepper to taste. Reserve.
To serve, make a bed of tomato sauce, remove the tuna from the frying pan and cut it into slices and place them in line on top of the sauce, a little aromatic olive oil with fried garlic and finally the grated nuts as if they were grated cheese.