Placer chicken pieces in a bowl. Mix salt, peppers, mustard, the cayenne pepper, paprika, garlic powder and file powder along with the Cajun spice. Rub about four teaspoons of this mixture all over the chicken. Reserve remaining spice mix.
Place the flour in a large bowl and add remaining reserved spice mixture. Mix well. Next, heat a large and then add the oil. Dredge the chicken pieces in the flour mixture to coat well on all sides and then gently shake off excess flour. Reserve the remaining flour and set aside.
When the oil gets hot and almost to the smoking point, place the chicken pieces into the skillet, skin side down. Cook about three minutes on each side until golden brown. Sear the chicken in batches and do not crowd the pan. Drain thoroughly on paper grocery bags or on paper towels.
Heat remaining oil over high heat until almost the smoking point and then stir in reserved seasoned flour. Stir the roux rapidly and constantly, using a wire whisk until it thickens and turns a golden brown. Be careful not to burn the roux. While you are making the roux, bring the broth to a boil in a large saucepan, on a separate burner.
Next, stir in the finely chopped onion, celery and green pepper to the roux. Cook the roux and vegetables for a couple of minutes and then remove from the heat.
Add about half of the roux and vegetable mixture to the broth, be sure to stir rapidly with the whisk. Gradually add the remaining roux, being sure to stir vigorously, throughout the process. Add the andouille sausage and stir for a bit. Continue to cook, stirring frequently from the bottom of the pot. Do this for about 15 minutes.
Finally, add the seared chicken pieces along with the bay leaf and the minced fresh garlic. Cook about an hour, on medium-low and be sure stir occasionally.
Using a slotted spoon, remove the chicken from the pot and allow to cool slightly. Next, cut the meat from the bones, discarding skin and bones. Shred the chicken slightly and return to the stew, be sure stir it in well. If using shrimp, add them to the pot, stir well and continue to cook over low heat for about 10 minutes. Prepare rice (or potato salad) and serve, spooning the rice into the gumbo.
When making the roux, adjust the amount of flour necessary to created a proper consistency. It should have a pasty consistency when it is finished.Consider giving the sausage a quick sear in a separate skillet, prior to adding to the gumbo. This will give it a nice finished texture and add a little sweetness from the caramelization process.You can substitute kielbasa for the andouille sausage. Either way, using smoked sausage will enhance the gumbo's flavor.White medium or long grain rice is best suited for gumbo as the shape and size of the rice grains is optimal for being coated with the sauce and that means more flavor and taste with every bite.Finally, and most important, as with all recipes, make this gumbo your own. Adjust the seasoning (and other ingredients) to your taste. There is never a reason for bland or over or under flavoring, you are at the wheel so make the journey memorable and delicious!