Drizzle the fish fillets with lemon juice, leave to stand for approx. 30 minutes, pat dry with kitchen paper and rub with salt.
Place each flour, breadcrumbs and eggs (beaten) on a dinner plate. Roll the fish fillets in flour, then in egg and then in breadcrumbs. Heat the butter and oil in a pan and fry the fish fillets for 4 - 5 minutes on each side over a medium heat until golden brown.