Cook the fish by grilling or poaching in the microwave
Remove the skin from the fish and break into large flakes
Season the mashed potato with salt and pepper
Gently mix in the fish flakes
Form the fish mix into four balls
Sift the flour into a shallow bowl
Roll the fish balls in the flour then flatten carefully to make patties
Beat the egg lightly in a shallow bowl
Put the floured fish patties in the egg mix and either turn carefully or use a pastry brush to cover the whole patty
Put the breadcrumbs in a shallow bowl and add the fish patties one by one, turning them to coat them well
Lay the patties out on a tray or plate, cover loosely and put in the fridge to chill for at least 30 minutes
When you are ready to cook, heat around half a cm of oil in a deep frying pan
Add the patties and cook on one side for 4-5 minutes
Turn each patty and continue to cook until the patties are evenly golden brown
Drain on kitchen roll and serve immediately