Clean, wash and cut the soup greens into small cubes. Peel and finely dice the onion. Wash the barley. Heat oil in a pot. Add soup greens, onion and barley and fry.
Add the stock, bring to the boil and cook for about 30 minutes. Mix egg yolk with cream and stir into the soup shortly before the end of the cooking time (do not let it boil any more. Season to taste with salt and pepper. Wash the chives and cut into fine rolls.
Pour soup onto plates and sprinkle with chives.