Traditional Polish Pierogi with Potatoes and Onions

Method

1. In a bowl, mix flour, egg, milk, and a pinch of salt to make a dough.
2. Knead the dough until smooth, then let it rest for 30 minutes.
3. Roll out the dough and cut into circles, fill with potato and onion mixture, and seal.
4. Heat oil in a pan and fry the pierogi until golden brown.
5. In a separate pan, caramelize the onion in butter until soft.
6. Serve the pierogi with the onions and a dollop of sour cream.