Salad "appetity"

Soak the herring, cut into pieces, pour over the lemon juice and let stand for 30 minutes. Cook the sauce. Mix kefir, mayonnaise, mustard and vegetable oil, add sugar, salt, pepper. Finely chop the boiled potatoes, onions and apple and stir with part of the sauce. Put pieces of herring on the dish, put the potato mixture on top with an even layer, on it with an even layer of beets grated on a coarse grater. Pour the salad with sauce, sprinkle with crushed spring onions.