Knead flour, butter, sugar, egg, lemon peel and salt to a smooth dough. Wrap in foil and chill for about 30 minutes.
Heat the apricot and strawberry jam in a small pot while stirring and let it boil down for about 5 minutes. Let it cool down while stirring occasionally.
Halve the dough and roll out to a rectangle (18 x 24 cm) on floured baking paper. Spread with strawberry or apricot jam and roll up from the long side using the baking paper. Put in the freezer for about 20 minutes.
Cut rolls into slices of about 1 cm thick and place them on 2 baking trays lined with baking paper. Bake the trays one after the other in the preheated oven in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 18-20 minutes. Cool down on cake racks.