Place the potatoes in a pot filled with water, bring to a boil and cook until soft.
Drain the potatoes and leave to steam dry for about 5 minutes.
Add the hot milk to the potatoes and mash using a masher until creamy. Season with salt and pepper.
Heat a pan with olive oil, season the fish on both sides with salt and pepper and cook until golden brown. Remove from the pan and using a fork and flake the fish.
Finely chop the chives, parsley and onion.
Add the fish, peas, chives, parsley and lemon zest to the mashed potato and mix through.
Using flour-dusted hands, shape the mixture into 6 cakes. (If the mixture is too soft, add some flour)
Place the whole wheat flour, panko and eggs onto 3 different plates.
First coat each fish cake with flour, then with the egg, and then coat with the panko breadcrumbs. Leave for 10 minutes in the freezer to set.
Heat a pan over medium heat, add sunflower oil and shallow fry the fish cakes until crispy and golden brown. Place on an oven tray and bake in the oven for a further 15 minutes, until warmed through.
For the tartare sauce: finely chop the onion, parsley and gherkins. Mix together with the mayonnaise, season with salt and pepper and add the lemon juice.
Serve the fishcakes with a side of green salad leaves and a helping of tartare sauce.
