Rinse fish fillets, pat dry and cut into 4 portions. Drizzle the juice of half a lemon over the fish.
Prepare three deep plates for the crumbing. Put the flour in the first, the lightly whisked eggs in the second and the breadcrumbs in the third.
Pat the fish fillets dry again and season with salt and pepper. Dip the fish fillets in the flour and gently tap off the excess. Dip into the whisked eggs, allowing the excess to drip off and then into the breadcrumbs, pressing down gently.
Heat the butter in a non-stick frying pan over medium heat and put in the fish fillets. Fry on each side for 2-3 minutes. Carefully turn so they do not fall apart. The best way is to use two spatulas.
Cut the other half of the lemon into 4 slices and use to decorate the fish. Serve with potatoes and a salad.