Combine first 7 ingredients in a small bowl. Set aside.
Preheat oven to 350 degrees.
In a Dutch oven, melt butter over medium-high heat. Add tasso and cook for 2 to 3 minutes.
Add chicken and cook for 3 to 5 minutes, stirring often. Add seasoning mix and half the onion, celery, and green pepper. Cook, stirring often, for 5 minutes.
Add garlic and cook 2 more minutes. Stir in tomato sauce, diced tomatoes, remaining onion, celery, and green pepper.
Add chicken stock and rice and stir to mix. Transfer mixture to 9-inch baking dish. Bake uncovered for 60 minutes. Stir well and remove bay leaves.