1. In a large skillet over medium heat, heat the oil. Add the celery and onion and saute until softened. Remove to a small bowl and reserve.

2. Melt butter in the skillet. Stir in the flour to make a roux, stirring briskly to incorporate.

3. Add the tomatoes with their liquid and cook 5 minutes.

4. In a large casserole or kettle over medium heat, heat the stock until it boils. Add the celery and onion mixture, seasonings, file, and okra and cook about 10 minutes.

5. Add the roux and tomatoes and heat until the soup thickens and reduces by one quarter, about 10 minutes. Remove from heat.

6. Add the poached chicken and shrimp and let them heat through about 2 minutes. Season with salt to taste. Transfer the soup to a serving bowl and serve hot. Add rice to each serving, if desired.