Put the raw milk in a saucepan, stir in yoghurt (alternatively a yoghurt starter culture from the health food store), cover, let stand for 2 days at room temperature.
When the milk is thick, carefully skim the cream into a mug with a tablespoon and place in the refrigerator. After a couple of hours in the refrigerator, smetana will thicken, then just stir until smooth and use. A good smetana should pull strings from the spoon.
From 3 liters of milk you get about 200 ml of Smetana. The remaining sour milk can either be made into quark or simply consumed as yoghurt.
Remarks:
Smetana is an indispensable part of Ukrainian cuisine and is used in a variety of ways. For example, in many Ukrainian dishes there is a mandatory smetana slap on top - whether it`s borscht, holubzi, varenyky or nalisnyky. Smetana is also used for the sauces, for the stoving for the Ukrainian national dish borscht or simply as a salad dressing.
Smetana has a much higher fat content than sour cream. An equivalent here in Germany would be something between crème fraîche and mascarpone.
Unfortunately, the recipe does not work with the homogenized milk from the supermarket. It only works with the untreated raw milk from the farm.