For the croissants, put the flour in a large bowl and make a well in the center. Add oil, salt, vinegar, crumbled yeast and sugar to the well.
Heat the mineral water and slowly add to the mixture. Knead until a smooth, not too firm dough is formed.
Cover the dough and let it rise in a warm place for about 45 minutes. Knead the dough again and roll out thinly.
Grate the cold butter over it (like cheese). Roll up the dough like a strudel. Cut the strudel in half.
Roll out both parts about 1 cm thick and cut into triangles. If desired, put a teaspoon of Nutella or jam on the wide side of the triangle and form croissants.
Place the Kipferl on a baking tray lined with baking paper and bake at approx. 180 °C until the Kipferl are golden brown.
Sprinkle the croissants with powdered sugar.
Preparation Tip:
The Kipferl m best still warm enjoy.