Step 1

For the dough, in a mixing bowl, combine 3 cups of the flour and the salt and stir together with a fork

Step 2

Make a well in the center and add the egg, water and oil

Step 3

With the fork, gently mix together the wet ingredients, then incorporate them with the flour and salt to form a shaggy dough

Step 4

Turn out the dough on a floured work surface and knead until you form a smooth, elastic, soft dough

Step 5

Add up to an additional 1 cup of flour, as needed

Step 6

Wrap the dough in plastic wrap and let the rest for about 20 minutes

Step 7

Meanwhile, make the filling

Step 8

In a medium skillet, heat a little neutral oil over medium heat and saute the yellow onion, stirring occasionally, until tender and golden

Step 9

Season with salt and pepper

Step 10

In a large bowl, mash the potatoes by hand, then add the cooked onion, cheese and salt to taste

Step 11

Mix until combined

Step 12

Before you get ready to roll out and fill your pierogi, gather a strainer or colander, wooden rolling pin, 3 ½-inch cookie cutter and sheet tray

Step 13

Fill a 6-quart pot with water, add a teaspoon of salt and bring to a boil

Step 14

Cut the dough in half, rewrap one half and lightly dust a work surface

Step 15

Roll out the first half, making sure it does not stick to your surface, to about ¼ inch thick

Step 16

Using the cookie cutter, cut out pieces close together, but not overlapping

Step 17

Reserve any scraps

Step 18

In the center of each cut piece of dough, place about 1 tablespoon of the filling

Step 19

Fold the dough over the filling, being mindful not to have any of the filling touch the edges

Step 20

Pinch the edges together; three times is the best

Step 21

Once this batch has been assembled, repeat the process with the other half of the dough and the scraps and the remaining filling

Step 22

To cook, place about 10 to 12 pierogi at a time in the boiling water and carefully stir to ensure the heat is evenly distributed

Step 23

Allow the pierogi to float to the surface

Step 24

Once they begin to "dance" on the top, transfer them to a colander

Step 25

To serve, melt some butter in a large skillet, add caramelized onion and pierogi and gently toss together

Step 26

Plate with dill on top and sour cream on the side