Mix all dry dough ingredients briefly. Add the butter, pistachio cream and soy drink and knead everything into a smooth dough. Preferably with your hands. The dough should no longer be sticky at the end. Wrap the dough in cling film and put it in the fridge for half an hour.
Preheat the oven to 160 degrees and line the baking sheet with baking paper.
Knead the dough again briefly and shape it into walnut-sized balls and press flat in the palm of your hand - place on the baking sheet and bake for about 14 minutes. Let cool down completely.
Put powdered sugar in a small bowl - add enough lemon juice until the consistency is mustard-like. Pour into a piping bag with the finest nozzle and decorate the cold cookies with it.