Boil the peeled potatoes in salted water for 25-30 minutes until soft.
Drain in a colander and let steam dry for 3 minutes.
Mash until smooth, return to pan, and beat in the milk.
Incorporate butter until fluffy, season with salt and white pepper, and keep warm.
Preheat the oven to its highest setting for the croutons.
Roast bread cubes on a baking tray for 4 minutes until golden.
Reduce the oven temperature to 200°C.
Season the dried pollock fillets with salt and white pepper.
Fry fillets skin-side up in foaming butter for 5 minutes until mostly opaque.
Turn the fish over and cook for another 3 minutes.
Transfer fish to a cold ovenproof pan and roast at 200°C for 4 minutes.
Boil chicken stock and water in the original frying pan.
Stir in capers, lemon, shallots, berries, and herbs then warm for 2 minutes.
Serve the fish over the potato puree topped with sauce, croutons, and remaining herbs.