In a large saucepan combine the stock, carrots, celery, onion and parsley. Bring to a boil, reduce heat and simmer until vegetables are tender.
In a mixing bowl, combine the matzo meal, 1/4 cup stock, 4 egg yolks, chicken fat or vegetable oil and salt and pepper. In another bowl, beat the egg whites until frothy but not stiff. Fold the egg whites into the matzo meal mixture. Refrigerate for 15 minutes. Shape the matzo mixture in to 2 inch balls while occasionally dipping your hands in cold water. Carefully add the balls to the simmering soup as you form them. Cover the soup and cook for 30 minutes. Serve hot.
If you are concerned if the oils or other ingredients in these recipes are suitable for Passover, seek non-dairy substitutes or ingredients that are certified kosher for Passover.