Wash and dry turkey breast inside and out.
Season turkey breast with cajun seasoning or seasoning salt and pepper.
Place celery sticks and onion pieces in bottom of slow cooker.
Place turkey breast on top of vegetables and cook on low in slow cooker for 6-8 hours, or until meat thermometer reads 165 degrees.
Remove turkey and set aside.
Strain juices through a colander into a medium sauce pan.
Whisk flour into water until smooth and then stir into turkey juices.
Cook over medium heat, whisking constantly until gravy thickens, adding more flour a teaspoon at the time if consistency is too thin.
Taste for seasoning and add salt and/or pepper if desired. If a more golden brown color is desired add Kitchen Bouquet Browning & Seasoning Sauce 1/2 teaspoon and the time.