Preheat the oven to 110°C/gas ¼. Cut the fish into strips about x2cm. Mix the Parmesan with the flour and turn the fish in it. Dip into the beaten egg, and then turn in the cornflakes till coated. Heat a few tablespoons of oil in a non-stick frying pan over a medium heat. Fry the fish fingers, in batches if necessary, until golden on all sides, about 5 minutes altogether, making sure not to pack the pan too tightly.