Mash the mashed potato with the cooked white fish or smoked mackerel fillets.
Add the onion/herbs and seasoning for flavour.
Shape or use cutters to get the desired effect.
Whisk the eggs and lay out the mixture in a bowl alongside a bowl of flour and a bowl of breadcrumbs.
Gently flour, egg and breadcrumb each fishcake.
Tidy up the shape if need be.
Bake for 20 minutes or shallow fry for 10 minutes on each side.
Serve with a healthy veg/mayo/tomato sauce.