Wash the potatoes. Cover and cook for about 20 minutes. Quench, peel and let cool off
Drain the mixed pickles and collect the stock. Mix sour cream, yoghurt, horseradish and 6 tablespoons of stock. Season to taste with a little salt and pepper
Cut the herrings into pieces. Wash the dill and chop finely except for a little bit. Add the mixed pickles, fish and dill to the sauce. Chill for at least 30 minutes
Cut the potatoes into slices. Peel and finely chop the onion. Fry both in hot oil while turning until crispy brown. Season the fried potatoes and serve with the fish. Garnish with dill and lemon
Drink: cold beer