Boil the chicken breasts in 6 1/5 cups (1.5 liters) of water. Once they are ready, remove them and tear them apart. In a pan, fry the chopped onion, carrot and pepper.
Pour them along with the oil in the chicken broth, put the pot on the stove and add the peeled and diced potatoes. Boil until the potatoes are half-softened. Add the torn chicken and rice.
Mix it well and season with salt and black pepper. Once the rice boils well, remove the soup from the heat.
Thicken it with beaten together egg, vinegar and yoghurt and add the chopped parsley.