Place the potatoes into a large saucepan of salted water. Bring to the boil and cook for 20 minutes until tender. Drain the potatoes and mash until smooth. Set aside to cool.
Meanwhile, break the cooked fish into large flakes, discarding the skin and bones if any and check for bones in the crabmeat by gently pressing a little at the time of crabmeat in-between your fingers.
Once the mash is cool enough, add to the fish and crab meat.
Add the sweet corn, and some lemon zest if desired. Season with salt and pepper. Mix carefully, trying not to break up the pieces of fish too much. Shape into 4-8 fishcakes and place on a baking tray lined with parchment paper . Leave to cool for 10 -15 minutes covered with cling film in the fridge.
Next prepare three large dishes. Place the flour in one with some seasoning, the egg in the second bowl and the breadcrumb in the third bowl.
Dip the cooled fishcakes into the flour and tap to remove the excess. Transfer them into the egg mixture then dip them into the breadcrumbs to create a crispy finish once cooking. Keep aside in the fridge until needed.
Heat a large non-stick pan over medium heat. melt the butter in a large non-stick pan over a medium-high heat with a drizzle of oil.
When the butter starts to foam, add the fishcakes and reduce the heat to low.
Fry for 3-5 minutes on each side until golden, turning them carefully once or twice.
Serve warm or at room temperature with extra salad leaves and some cherry tomatoes and lemon wedges.
