For the potato brioche pastry, boil potatoes, peel and strain while hot. Mix the yeast with a little water and sugar, dust with a little flour and let the dampfl rise, covered, in a warm place. Knead briefly with remaining ingredients and shape as desired (small loaves the size of jour cookies, sticks, etc.).
Place on a greased baking sheet, brush with egg yolk and let rise. Bake the potato brioche pastry in the preheated oven at approx. 180°C for approx. 15-20 minutes, depending on size.