Peel the potatoes, cut into pieces and boil in salted water for twenty minutes until soft. Drain and return them to the pot. Add butter and mash into a smooth purée. Season with more salt if needed.

On a floured worktop, roll the dough into a sheet about 1 cm thick. Cut out rounds, using a glass if you don't have a cutter.

Heat a generous layer of oil in a pan. Add the rounds and fry on both sides until golden. Transfer the pancakes onto a kitchen towel to soak up the excess oil, then let them cool.

Season the soured cream to taste – you can also stir in a little chopped dill if you like. Arrange the potato pancakes on a plate. Top each one with a dollop of soured cream, a slice of marinated fish, and garnish with a sprig of dill.