Matzo Ball Soup

Name: Matzo Ball Soup
Ingredients: 1 tablespoon vegetable oil; 1 large yellow onion, diced; 4 stalks of celery, diced; 4 or more carrots, peeled and diced; 2 whole fat chickens; 2 eggs; 2 tablespoons schmaltz; 2 tablespoons soup stock or water; ½ cup matzo meal; 1 teaspoon salt, and more to taste; Black pepper, to taste