Polish Pierogi Z Ziemniakami with Fermented Dough

Method

1. 1. In a large bowl, mix both flours and yeast.
2. 2. In a separate bowl, combine warm milk, egg, softened butter, and salt.
3. 3. Gradually add the wet ingredients to the dry ingredients, mixing until a dough forms.
4. 4. Knead the dough on a floured surface for 10 minutes until smooth and elastic.
5. 5. Place the dough in a greased bowl, cover with a cloth, and let it rise in a warm place for 1 hour or until doubled in size.
6. 6. Roll out the dough and cut into circles.
7. 7. Place a spoonful of mashed potatoes and onions in the center.
8. 8. Fold the dough over and seal with an egg wash.
9. 9. Boil in salted water until they float.
10. 10. Sauté in butter until golden and serve.