Place the spring onion, ginger and daikon radish in a bowl of ice-cold water. This will help to keep them crisp.
Heat the sunflower oil in a small frying pan over medium heat. Fry the garlic until golden brown. Use a slotted spoon to transfer the garlic to a bowl and remove most of the excess oil from the pan with paper towel, leaving a little behind for the tuna.
Heat the pan o