First mix the marinade. Mix together mayonnaise, skimmed milk yoghurt, creme fraiche, chopped walnuts, wine vinegar and lemon juice. Season to taste with sugar, pepper and salt. Let rest in the refrigerator for about 20 minutes.
Cut herring fillet, beetroot, pickles, apples, onions, beef and potatoes into small cubes and stir. Mix the marinade with the mass. Whip the cream and fold in.
Also suitable as a spread. Tastes very good with black bread.