Mix butter, vanillin sugar, salt and 50 g icing sugar with the whisk of the hand mixer until creamy. Stir in the egg and grated zest of 1 lemon. Stir in flour. Pour the dough into a piping bag with star-shaped spout (11 cm Ø) and squirt approx. 25 flowers (stems 4 cm long, total length 8 cm) onto 2 baking trays lined with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 10 minutes.
Remove and let cool off. Mix 125 g icing sugar with juice until smooth. Spread the biscuits with the juice. Sprinkle with pistachios and grated zest of 1 lemon. Leave to dry
waiting time approx. 1 1/2 hours