Finely chop the vegetables and sauté them in olive oil. Add the meat and the water, salt and pepper and let it boil over medium heat for about 1 hour or a bit longer until the meat is tender.

Remove the meat and mash the vegetables. Remove the bones from the tail pieces and add the meat in the soup.

Serve the soup and garnish the plates with the yogurt mixture, which is prepared as follows: Mix in the yogurt with the olive oil, the juice and the lemon gratings and the freshly ground pepper. You can even add finely chopped tender celery leaves.