Place turkey bones in a large Dutch oven; add water, celery, carrot, and peppercorns. Bring to a boil; cover, reduce heat, and simmer 1 1/2 hours. Strain broth through a cheesecloth- or paper towel-lined sieve; discard bones, vegetables, and peppercorns. Cover broth, and chill thoroughly. Skim and discard fat from top of broth. Reserve 1 3/4 cups broth, and set aside.
Coat a small saucepan with cooking spray; add oil. Place over medium heat until hot. Add flour; cook, stirring constantly, 6 minutes or until lightly browned.
Add onion and celery to saucepan; cook 2 minutes, stirring frequently. Add 1 3/4 cups reserved broth and okra; bring to a boil, reduce heat, and simmer, uncovered, 10 minutes. Add cubed Roasted Turkey Breast and remaining ingredients; bring to a boil. Reduce heat, and simmer, uncovered, 20 minutes. Remove and discard bay leaf.
Note: You can use 1-3/4 cups undiluted no-salt-added chicken broth instead of making a broth from the turkey carcass.