Sieve the flour onto the work surface. Cut the butter into small cubes and spread on the flour with the egg yolk, sugar, grated almonds, cinnamon powder and the grated zest of half an untreated lemon. Knead all ingredients quickly into a smooth dough, shape into a ball, wrap in foil and refrigerate for at least 30 minutes. Form thin rolls from the dough on the work surface, cut off small pieces, roll into thin strands and shape into small rings. Place well apart (the rings diverge a lot) on a baking sheet lined with baking paper and bake in a preheated oven at 180 ° C for about 10 - 15 minutes.
Put plenty of cinnamon sugar in a soup plate. Carefully turn the hot Ringerl in it and leave to cool on a wire rack.