Pre-cool the oil. Measure the flour and sift into a separate bowl. Line a baking tray with baking paper.
In a deep bowl, combine flour, salt and cold butter. Grind everything with your hands until crumbly. Add sour cream to the resulting crumbs and knead the dough well until all ingredients are completely moistened. Wrap the finished dough in film and put it in the refrigerator for 30 minutes.
Divide the dough into 2 parts. Roll out each part to a thickness of 1-2 mm. Roll the rolled out rectangles into a roll, sealing the seam well. Cut into 10cm cubes and dip the top side in sugar. Place on a baking sheet and bake in the oven at 160 degrees for 30 minutes.
Serve sprinkled with powdered sugar.