Separate eggs. Beat the egg whites with 3 tablespoons of lukewarm water with the whisks of the hand mixer until stiff. Gradually add sugar and vanillin sugar. Stir in egg yolk. Mix flour, cornstarch, cocoa and baking powder, sieve over it and fold in with a whisk. Lightly grease a baking tray and line it with baking paper.
Spread the sponge cake mixture on it. Bake in a preheated oven (electric: 200 °C/ gas: level 3) for 10-12 minutes. Sprinkle a tea towel with sugar. Fold the sponge cake base onto it. Carefully remove the paper. Roll up the sponge immediately with the help of the cloth and let it cool down. Soak the gelatine. Wash the lemon, grate and dry the peel. Halve the lemon and squeeze it. Place the lemon peel and juice in a saucepan with sugar. Heat at low temperature while stirring until the sugar is dissolved. Squeeze the gelatine, dissolve and allow to cool.
Wash the lemon, grate and dry the peel. Halve the lemon and squeeze it. Place the lemon peel and juice in a saucepan with sugar. Heat at low temperature while stirring until the sugar is dissolved. Squeeze the gelatine, dissolve and allow to cool. Place in a cool place. Whip cream and vanillin sugar until stiff. As soon as the lemon juice starts to gel, fold in the cream. Roll the sponge roll again and spread with lemon cream. Roll up again, press down lightly and put in a cool place. Dust the sponge roll with icing sugar, cut open and decorate with lemon balm as desired. Results in approx. 15 slices
Whip cream and vanillin sugar until stiff. As soon as the lemon juice starts to gel, fold in the cream. Roll the sponge roll again and spread with lemon cream. Roll up again, press down lightly and put in a cool place. Dust the sponge roll with icing sugar, cut open and decorate with lemon balm as desired. Results in approx. 15 slices