Season the chicken with salt, pepper, and paprika.Place chicken breast on a small baking sheeting and broil for about 10 minutes, or until browned.
Place the chicken on the bottom of a 2-quart slow cooker.
Add the onion, celery, green pepper, tomatoes, tomato paste, creole seasoning, thyme, tapioca, and mushroom over the chicken.Cover the slow cooker and cook on low setting for 4-5 hours.
Shred the chicken with a fork and stir to mix.
When ready to serve, prepare the instant rice and serve.