Clean the gizzards well and put them to boil with 3 1/5 cups (750 ml) of water. Let them bubble for 10 minutes and remove them from the fire. Drain them from the water and cut them into small pieces.
In another pan, heat a little oil and sauté the grated onion and carrots. Add 4 1/5 cups (1 liter) of hot water and drop the gizzards and potatoes in. Allow the soup to simmer until the potatoes stew and add salt, black pepper, grated tomato and vermicelli.
After about another 10 minutes, remove the soup from the heat and thicken it with the beaten egg with yoghurt and 1 tsp vinegar. Add finely chopped parsley. Serve warm with rustic bread.