1. In a large pot or dutch oven, melt 2 tablespoon butter over medium-low heat. When foamy, add the onion, celery, red peppers and salt and cook for 5-7 mins, stirring occasionally. Add garlic and cook 5 more mins until the onions begin to turn translucent.
2. Add the chicken stock. Add the black pepper, cayenne pepper and stir to combine. Bring to a boil, then reduce to simmer and cover.

For the rice

1. Combine 1 cup rice, 2 cups water, and 1 teaspoon salt. Bring to boil, cover, and let simmer over low heat for 14-15 mins.
2. Meanwhile, slice the sausage and add to a skillet. Turn the heat to medium, and cook, tossing occasionally until browned, about 7-10 mins. Using a slotted spoon, transfer the sausage to the chicken stock. Pour off any excess fat left in the skillet.
3. In the same skillet, melt 2 tablespoon butter. When foamy, add 2 tablespoon flour and whisk until incorporated and the roux is light brown and fragrant, about 2-3 mins. Add to chicken stock, and stir, then add file powder and stir until it is well incorporated.
4. Add the shrimp, turn off the heat, cover and allow to sit for 10 mins before serving. Serve over rice.