You will need
    • milk – 1 liter;
    • the yeast – 2-3 tablespoons;
    • thermos.
Boil the milk in a regular pan and then cool to 40-45 degrees. To check the temperature without using a thermometer, simply place a clean finger in the milk – if within 10 seconds you will not feel discomfort, that is, the finger will be warm, but not hot, it means that the milk is ready for making yogurt.
Add in the warm milk the yeast and stir thoroughly with a whisk. The role of the starter culture may be a special starter culture for yoghurt, and the usual "live" yoghurt, that is, one whose shelf life does not exceed 14 days.
Quickly and thoroughly mix the yeast with the milk, pour the mixture into a prepared flask. Before you use a thermos, it should pour boiling water in addition to dairy bacteria do not multiply additional.
Wrap the thermos in a towel or blanket and put in a warm place. In winter you can put it near the battery, in the summer – in the sun. In this position, the thermos of the future of yogurt is left to 4-7 hours.
After the specified time, open the thermos, and yogurt, pour into jars or other containers. Jars put in the refrigerator for 2 hours. This is necessary to stop the growth of milk bacteria and the yogurt was not sour. The yogurt is ready.