Prepare the dough. In a bowl, thoroughly mix water, egg 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 begins to thicken - with your hand. The dough must be thoroughly kneaded, grabbing 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 fridge, prepare the filling. Boil the potatoes and mash them. Mince the slightly frozen lard or grate it on a fine grater. Prepare the frying for the finished dumplings. Finely chop the lard and onion and fry them over medium heat for about 5 minutes until golden brown. Remove from heat. Mix the lard, onion and puree.
Start making the dumplings. Sprinkle a little flour on the table, take the dough out of the fridge, roll it out with a rolling pin into a layer about 1 mm thick. Take a glass or cup and cut small circles. Roll the rest of the dough into a "sausage", cut into small pieces and roll out the circles by hand. Put the filling in the center of each circle and pinch 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 that they don’t stick to the bottom. After about 2 minutes, as soon as the dumplings float to the surface, take them out and serve, pouring over the fried mixture with cracklings.