Separate eggs. Beat the egg whites, 2 tablespoons of cold water and salt with the whisks of the hand mixer until stiff. Gradually add 150 g sugar and 1 packet of vanilla sugar. Add the egg yolks and stir carefully. Sift the starch, flour and baking powder over the egg yolks and fold into the egg foam using a whisk. Line a baking tray with baking paper, spread the sponge cake mixture on top and bake in a preheated oven (electric range: 200 °C/ gas: level 3) for approx. 15 minutes.
Turn out onto a tea towel sprinkled with sugar. Carefully remove the baking paper and cover the sponge cake with a damp cloth. Let it cool down. Soak the gelatine in cold water. Whip cream, remaining sugar and vanilla sugar until half stiff. Squeeze the gelatine and melt it in a pot at low heat. Add to the cream, stirring constantly, and beat the cream until stiff. Spread the sponge with cream and spread the frozen fruit on top. Press on a little bit. Roll up the sponge plate from the long side using the cloth. Chill for about 1 hour.
Squeeze the gelatine and melt it in a pot at low heat. Add to the cream, stirring constantly, and beat the cream until stiff. Spread the sponge with cream and spread the frozen fruit on top. Press on a little bit. Roll up the sponge plate from the long side using the cloth. Chill for about 1 hour. Dust the sponge roll with icing sugar, cut it into pieces and decorate as you like with cream tuffs, fruits and lemon balm. Results in about 10 pieces