In a 4-quart saucepan, combine broth, and 1 1/3 cups water, vegetables, meatballs, onions, basil, salt, and black pepper. Bring to a boil. Reduce heat to low and cover. Simmer for ten minutes, or until vegetables are tender. In a screw-top jar, combine flour and remaining water. Shake well. Gradually, stir into stew. Cook until thickened and bubbly, stirring frequently.