How to make
Cut the zucchini and potatoes into small cubes and boil them in salted water. Once they are cooked, leave the soup to cool slightly, then thicken with the pre-mixed yogurt and egg.
To prevent curdling, pour part of the broth into the mixture and then pour everything into the soup while stirring constantly.
Allow to cool completely. Serve cold with fresh parsley, torn by hand on top.