Dough: Beat eggs, sugar, vanilla sugar for 5-7 minutes until thick and creamy. Beat in the fruit vinegar. Fold in the flour and baking powder. Bake for about 15-20 minutes at about 150 degrees.
Topping: whip the sour cream, preserving sugar and lemon juice until creamy. Whip the whipped cream until stiff and stir into the sour cream. Chill the cake for at least 12 hours.
Soak the gelatine and fold in the red fruit jelly. Put on top of the cake and chill again for at least 30-40 minutes.