Turkey and Herb Dumpling Soup

Name: Turkey and Herb Dumpling Soup
Ingredients: 1 large onion, chopped (1 cup); 2 stalks celery, chopped (1 cup); 2 carrots, chopped (1 cup); 1 pound piece roasted skinless, boneless turkey breast (see Tips); 3 cups no-salt-added chicken stock or broth; 3 cups water; ¼ teaspoon black pepper; 1 ½ cups self-rising flour; 1 tablespoon chopped fresh parsley; 1 tablespoon chopped fresh sage or 1 teaspoon dried sage, crushed; 1 tablespoon chopped fresh thyme or 1 teaspoon dried thyme, crushed; 3 tablespoons margarine, melted; 3 tablespoons fat-free milk; 1 egg, beaten