3 days before for the fish peel, wash and cut carrots and horseradish into small cubes. Peel onions and cut or slice into thin rings. Coarsely crush laurel, pepper, pimento and mustard seeds in a mortar. Then boil everything up in a pot with vinegar, 5 tablespoons of water and sugar. Let the brew cool down lukewarm.
Put the matie in cold water for about 20 minutes. Drain, dab dry and cut into bite-sized pieces. Put them into a closable container and pour the stock over them. Leave closed for approx. 3 days in the refrigerator.
After 3 days wash potatoes and boil them in water for about 20 minutes. Stir sour cream and sour cream until smooth. Season to taste with salt and pepper. Drain the potatoes. Serve herring with potatoes and cream sauce.