Preheat the oven to 180°C/fan 160°C/gas mark 4. Lightly grease a baking tray.
Mix the fish with the mashed potato, herbs and lemon zest and season well with salt and pepper. Add a little beaten egg if necessary to bind the mixture together.
Divide the mixture into 4 even sized pieces then shape into a star using a cookie cutter or cut into a star shape using a knife.
Place the flour, remaining egg and breadcrumbs into three separate dishes. Take each fishcake, cover in flour, then egg, then breadcrumbs and place on the prepared baking tray. Bake for 15-20 minutes until piping hot and the outside is golden and crunchy.