Peel the potatoes and cut into cubes. Put to boil in 1.5 liters of salt water. Separately, boiled lentils, kochto cleared overnight and left to soak in water. From the butter and flour roux is made which is diluted with water from the potatoes. Was added thereto and boiled potatoes and lentils, add salt, put and pepper and leave to boil a little. Remove from heat and bind with beat eggs with yogurt. Optional soup can be served with fried bread cubes (croutons).