Add flour, salt, and oil to a bowl or pot. Boil water.
Pour a cup of hot water to the bowl and mix with a spoon.
Once the mixture cool down a little, start working the dough with your hand. Work the dough for about 5 to 10 minutes, add flour so it does not stick to your hands. Form a ball and set aside.
Add cooked mushrooms and sauerkraut together. Blend them until smooth consistency.
Dust the cutting board generously with flour.
Cut a piece of dumpling dough and use a rolling pin to flatten it (around 2 mm).
Use a glass to cut even circles in the dough.
Fill each circle with about ½ tsp of mushrooms and sauerkraut mixture.
Fold the circle in half.
Glue the circle rim with your fingers.
Use your thumb to make a flounce. Press a half-circle rim in with your thumb.
Put the dumpling on the dusted cutting board and repeat the folding steps.
Bring a big pot of water to a boil. Add 1 tsp of salt and 1 tsp of oil.
When the water is boiling, put the dumplings in (we recommend 10 dumplings at once). Stir them with a spoon carefully.
Boil the dumplings until they float to the surface.
Fish the dumplings out with a skimmer. Put them on a plate so that they do not touch each other. Repeat the cooking steps.