Pour milk into a saucepan and tepefy. Pour it into a plastic bottle or carafe, cover with a dense towel, tie and leave in a warm place. Milk souring takes 2 days on the average, but in cold weather it may take 5 days. Do not mix or shake the liquid during this entire period. Place a colander over a saucepan or a bowl, cover it with several layers of gauze and turn the contents of the container with acidified milk into the colander. Leave it for a while until all the liquid drains off. This process may take about 1.5 hours. Put the remaining gelatinous mass in a bowl and whip it properly using a blender. You can obtain the desired consistency by adding milk. Put the mass in a jar, screw the lid onto the jar and refrigerate for half an hour.