Pour the flour on a counter or other surface that will allow you to make the dough

Add a pinch of salt

Make a little whole in a middle and start adding milk and butter

Add a little water at the time and work the dough until you can form a ball about 10-15 minutes

Once done, cover it with the big bowl and let it rest for about 20-30 minutes

Use 1/4 of the dough at the time, covering the remaining with the plastic wrap

Roll the dough until thin (like pasta) and using either cookie cutter or large wine glass cut the circles

Place 1 teaspoon of fling in the middle of the circle

Wet one half of the circle and then seal it together

Boil large pot of water and season with salt

Once the water is boiling put about 8 pierogi at the time

Once they come to the surface let them cook for 1 minute and using spider or slotted spoon take them out on a plate

If you are not serving pierogi immediately, take them out on a counter and let them cool down and dry a little bit. Make sure that they are not touching each other. Once cooled, place them on a baking sheet, again with distance from each other, place in a freezer and let them freeze. Once done, you can pack them in the plastic bag.

Place dried mushrooms in a pot of water and let it stand, preferably overnight

The day of making pierogi, cook porcini mushrooms in the water that they soaked in

Rinse the sauerkraut and place in another pot, cover with water and cook for about an hour

In the meantime heat up 1 tablespoon of oil, add chopped onions and cook until soft, about 5 minutes

Add sliced fresh mushrooms to the onions and cook until soft, about 15 minutes

When dried mushrooms are cooked, remove them from the water with slotted spoon, reserve the water

Rinse them well under running water to make sure that they are perfectly clean

Once all your ingredients are cooked, you can add sauerkraut, fresh mushrooms and dried mushrooms to the food processor and process until finely chopped but not mushy

Placed processed filling back to the pan and using strainer add 1/4 to 1/2 cup of dried mushrooms water and cook for a few minutes

Check for seasoning, add salt and pepper and cook for few more minutes until all the ingredients are merged.

Let it cool before starting to assemble pierogi.