Separate eggs. Beat the egg yolks and 25 g sugar until fluffy. Beat the egg whites until stiff, pour in 25 g sugar. Fold into the egg yolk mixture with sieved flour. Spread on a baking tray (approx. 35 x 40 cm) lined with baking paper. Bake in a hot oven (electric cooker: 200 °C / convection oven 175 °C / gas: level 3) for 8-10 minutes
Turn the sponge onto a damp tea towel. Peel off the baking paper and let it cool down. Soak gelatine in cold water. Wash, clean and puree the strawberries. Stir in 2 tbsp. sugar and vanillin sugar. Squeeze the gelatine, dissolve. Stir in some puree, then stir into the rest of the puree. Cool until the mixture gels
Whip the cream until stiff. Chop the chocolate. Fold both into the puree. Cut sponge cake crosswise into 3 equal pieces. Spread strawberry cream on top. Roll up each piece from the wide side. Cut each roll into 4 pieces, dust with icing sugar and decorate