Put the chicken in a pot with about 4L of water, and bring to a boil.
When the water starts to boil, a foam will form on top. Clear it.
When there is no more foam forming, add the vegetables.
Simmer for around 40 minutes, until the meat and the vegetables have cooked.
Strain the soup in another pot, through a sieve.
Blend all vegetables, except for two carrots.
Cut the carrots into small pieces, and shred the chicken.
Make the dressing for the soup. Mix the sour cream with the garlic, egg yolk, and salt. Whilst whisking continuously, start adding ladle after ladle of hot soup. Do so until the temperature of the sour cream mixture reaches the same temperature as the soup. Then pour it over.
Bring the soup back to boil, and return the blended vegetables, the carrots, and the shredded chicken.
Add the vinegar, mix well, and turn the heat off.
Serve the soup hot, topped with the herb of your choice, with additional vinegar and sour cream on the side.