Wash the lemons hot and grate them dry. Grate the zest of 1 lemon. Halve the lemon and squeeze it. Separate the eggs. Beat the egg whites until stiff, then add 75 g sugar. Stir in egg yolks, lemon juice and zest.
Mix flour, starch and baking powder, sieve over the mixture and fold in. Put the sponge mixture on a baking tray (32 x 39 cm) lined with baking paper and smooth it down. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 10-12 minutes. Take out the sponge cake and turn out on a tea towel sprinkled with sugar. Peel off the paper. Roll the sponge cake with the tea towel from the long side and let it cool down. Tear zests from the remaining lemon, cut lemon in half and squeeze. Mix lemon juice, zests and sour cream. Stir the Gelatine-Fix into the sour cream with the whisks of the hand mixer on the lowest setting. Continue stirring for 1 minute. Allow 75 g sugar to trickle in and continue stirring at the lowest setting.
Tear zests from the remaining lemon, cut lemon in half and squeeze. Mix lemon juice, zests and sour cream. Stir the Gelatine-Fix into the sour cream with the whisks of the hand mixer on the lowest setting. Continue stirring for 1 minute. Allow 75 g sugar to trickle in and continue stirring at the lowest setting. Whip the cream until stiff and fold in. Place the raspberry jelly in a bowl and whisk until smooth. Roll out the sponge cake. Spread the jelly first, then the cream on the sponge cake. Roll up the sponge again from the long side using a tea towel and chill for at least 2 hours. Take out the roll, dust with icing sugar and decorate with lemon zests
Whip the cream until stiff and fold in. Place the raspberry jelly in a bowl and whisk until smooth. Roll out the sponge cake. Spread the jelly first, then the cream on the sponge cake. Roll up the sponge again from the long side using a tea towel and chill for at least 2 hours. Take out the roll, dust with icing sugar and decorate with lemon zests