Beat the egg whites until stiff, adding 200 g sugar. Continue beating for about 10 minutes until a smooth, firm, shiny mixture is obtained. Sift 2 teaspoons of starch on top, add vinegar and fold in.
Draw 2 diagonally offset circles (each approx. 20 cm Ø) on a piece of baking paper, turn over the baking paper and place on the baking tray. Spread the beaten egg white on the visible circles and spread with a spoon (approx. 2 cm thick).
Bake in a preheated oven (electric cooker: 100 °C/ convection oven: 75 °C/ gas: see manufacturer) for approx. 1 hour. Then reduce the temperature (electric oven: 80 °C/ convection oven: 55 °C/ gas: see manufacturer) and continue baking for approx. 1 hour.
Let meringue cool down in the switched off oven.
Meanwhile, bring cherry nectar, 75 g sugar and vanillin sugar to the boil in a large pot. Mix 2 tablespoons of starch and 4 tablespoons of water and pour it into the boiling nectar while stirring. Let it simmer for 2-3 minutes at low heat.
Keep stirring constantly. Add the frozen berry mixture to the thickened nectar, heat up again and simmer for 2-3 minutes. Red fruit jelly in egg
Whip the sour cream and 50 g sugar with the whisk of the hand mixer until creamy. Whip the cream until stiff, allowing the cream firmer to trickle in. Fold the cream into the sour cream.
Remove the bases from the baking paper. Place one of the bottoms on a plate. Carefully spread the sour cream on the meringue bases with a spoon. Spread some red fruit jelly on the meringue base on the plate.
Place the second meringue base on top. Put some red fruit jelly on top. Add the remaining grits.