Wash the meat well and put it to boil in a pot with water. Once boiling, pour out the water, rinse the meat again and pour in new, cold water. Add the chopped onions, pepper, celery and grated carrot. Add a little oil, salt and leave to boil until the meat is ready.
Tear the boiled meat (remove bones if present) into small pieces and return them to the broth. Add the cleaned and washed rice, leave to boil for 10 min. Take the pot off the stove and leave to cool for a bit.
In a metal container, beat the egg with a fork, add the yoghurt, flour, a pinch of citric acid, the lemon juice and pour in the water.
Put it on low heat, while stirring nonstop, until the thickening agent comes to a boil. Once boiling, pour the thickening agent into the soup and stir until the soup becomes smooth and nice.
Sprinkle with black pepper and finely chopped parsley, stir and put the lid on the pot for 10 min. Serve!