Peel the fish from the skin and divide it into fillets, pull out all the bones.
Cut carrots, eggs, onions, peppers, greens finely, cut cucumbers into thin rings. Dissolve gelatin in 40 ml of water and pour it into sour cream. Mix vegetables with sour cream, season to taste and add lemon juice.
Put the finished stuffing on one fish fillet and cover with the second.
Wrap stuffed herring tightly in cling film, tie ends and refrigerate overnight.
Remove the film and cut with a sharp, warm knife into portions.