Peel and dice the potatoes, then cook them in slightly salted water. Drain and mash with a fork.
Steam the fish over hot water for 5 minutes. Remove the skin, then carefully flake them into chunks.
Beat the egg then add to the potatoes together with the fish and lemon zest. Season with salt and pepper to your liking. Gently combine.
Make patties with your hands and put them on a plate. Chill until you’re ready to cook them.
Brush both sides of the fishcakes with olive oil and bake them at 180 C in a preheated oven - or fry them on both sides until golden brown.
Serve warm or at room temperature.