For the dough: add warm drinking water, yeast and sugar to the slightly warm milk and stir. Sift flour, make a groove in the middle and pour in the resulting liquid. Add melted and cooled oil. Salt and knead soft dough. Put in a warm place, cover and leave to rise for 40-50 minutes. For the filling: wash potatoes, put in a saucepan, cover with boiling water and cook until done for about 25 minutes. Then drain the water, peel the potatoes and mash them until smooth. Mash the fresh cheese and mix with potatoes, add sour cream, salt and stir. You can add thyme. Knead dough into a 7-10 mm flat cake with your palm. Place the minced meat in the middle and make even. Then, taking the ends of the dough, draw them in to the middle, connect and pinch. Level the surface of the pie, stretching it so as to obtain a round flat cake of even thickness. Make a cut in the dough atop in the middle for the steam outflow. Bake the pie in the oven preheated to 200 °C for 15-20 minutes. Take out of the oven and oil at once.