Ukrainian Potato Pierogi

Method

1. In a bowl, mix the flour, egg, and water to form a dough. Knead until smooth, then let rest.
2. Mash the potatoes and mix with sour cream, salt, and pepper.
3. Roll out the dough and cut into circles. Fill with the potato mixture, fold, and seal.
4. Boil the pierogi until they float, then fry with onions in butter and serve.