Pour water into the pan. Sift the flour through a sieve twice. Remove the mixing bowl and a towel to cover the dough while it rests. Have a rolling pin and a glass or cup ready to cut out the dough. Don't forget a slotted spoon to remove the finished dumplings.
Prepare the dough. In a bowl, thoroughly mix the water, eggs and salt until smooth, beating them with a fork for about 4-5 minutes.
Start adding flour, stirring the dough with each new portion: first with a spoon, and when it starts to thicken, with your hand. The dough must be kneaded thoroughly, moving from the edges to the center. After that, cover it with a towel and put it in the refrigerator for 30 minutes. During this time it will become elastic and pliable.
While the dough is in the refrigerator, prepare the filling. Add sugar and salt to the cottage cheese and, if necessary, egg yolk. Mix thoroughly until smooth.
Start making dumplings. Sprinkle the surface of the table with flour, remove the rested dough from the refrigerator and roll out a layer with a rolling pin to a thickness of approximately 1 mm. Take a glass or cup and cut small circles. The remaining dough can be rolled into a “sausage”, cut into small pieces and rolled out into circles by hand.
Place the filling in the center of each circle and seal the edges. The seam should be tight enough not to fall apart.
Boil the dumplings. Throw them into the water and stir with a slotted spoon so they don't stick to the bottom. After 2 minutes, as soon as the dumplings float, take them out and serve.