1¾cups chopped or thinly sliced smoked sausage such as kielbasa (see note)
2cups cooked rice
Put the chicken pieces in a bowl. Blend the salt, black and white peppers, mustard, cayenne pepper, paprika, 1teaspoon garlic, and filé powder. Rub 4teaspoons of the mixture over the chicken. Reserve 2teaspoons of the spice mixture and discard the rest.
Put the flour and the reserved spice mixture in a bowl. Blend well.
Heat a 10-inch black iron skillet and add the oil. Dredge the chicken pieces in the flour mixture to coat well, shaking off the excess. Reserve the leftover flour.
When the oil is hot and almost smoking, add the chicken pieces, skin side down. Cook about 2 minutes on one side until golden brown. Turn and cook about 3 minutes on the second side until nicely browned. Drain thoroughly on paper towels.
Pour off all but 1cup of fat from the skillet. Heat this oil over high heat until it is almost smoking and add the reserved seasoned flour. Stir rapidly and constantly with a wire whisk until the mixture starts to look like dark chocolate. Do not burn. This is a roux.
Add the chopped onion, celery, and green peppers to the roux and stir to blend well. Remove from the heat without allowing it to burn.
Meanwhile, bring the stock to a boil in a large saucepan.
Add about ½cup of the roux mixture to the stock, stirring rapidly with the whisk. Continue adding the roux mixture to the stock, ½cup at a time, always stirring rapidly and constantly.
Add the smoked sausage and stir. Cook over high heat, stirring often from the bottom, about 15 minutes.
Add the chicken pieces, bay leaf, and remaining teaspoon garlic. Continue cooking about 40 minutes.
Remove the chicken pieces. Cut the meat from the bones and discard the bones. Cut the chicken meat into cubes and add it to the gumbo. Serve with rice spooned into the gumbo.