Debone smoked turkey, trying not to shred meat. Cut turkey meat into manageable bite-size pieces, about 1 inch in size. Refrigerate turkey meat for later use in recipe. Place turkey carcass in a large (14-quart) stockpot.

Remove and reserve ends from celery. Remove and reserve ends and skins from all onions. Quarter medium-size onion. Quarter all bell peppers, and remove and reserve membranes; discard seeds. Add celery ends, pepper membranes, and onion ends and skins to pot, along with quartered onion, 4 whole celery stalks, and quarters from 1 pepper. Store remaining vegetables, covered, in refrigerator for later use.

Cover with water, and bring to a roaring boil over high; reduce heat to medium, and bring mixture to a simmer. Cook, at a steady simmer, until reduced to 8 quarts of stock, which will take up to 8 hours. Remove turkey carcass and vegetable pieces, and discard. Pour stock through a wire-mesh strainer over a large bowl to remove remaining solids; return strained stock to stockpot.

Stir together flour and oil in a medium-size cast-iron pan with a slotted, flat spatula. Stir until mixture is thoroughly combined and lumps or bits of flour are no longer visible. Cook mixture over medium, stirring constantly, until it is dark brown in color (think of an aged penny), between 35 minutes and 1 hour and 15 minutes. (This process depends on the heat, which varies from stove-top to stove-top, and the aggressiveness of the cook. Patience is very important.) If the roux burns, throw it away and start over. A burned roux cannot be used. The spatula should constantly rub or scrape the bottom of the pot to prevent mixture from sticking and burning. If the roux begins to clump, whisk out the clump with an aluminum whisk. Once roux has reached desired color, remove pan from heat; continue stirring until slightly cooled, about 10 minutes. (The roux will continue to cook as it cools.)

Bring stock to a light boil, and carefully stir in cooled roux. Stir until roux has completely dissolved into stock, giving stock a dark brown color. (At this stage, mixture will be very bitter and taste flat.)

Lightly boil mixture, stirring constantly, 45 minutes. Continue to cook, stirring occasionally, 25 minutes longer.

Add andouille sausage, in batches, to stock mixture. (Adding in batches prevents mixture from cooling down too much.) Cook, stirring occasionally, 45 minutes.

Meanwhile, dice remaining refrigerated celery (6 stalks, about 1 1⁄2 cups), peppers (2 peppers, about 1 cup), and onions (2 small onions, about 2 cups). Keep diced vegetables separated.

Stir the minced garlic into the stock; stir in the “trinity” (diced celery, peppers, and onions), 1 vegetable at a time, adding onions last. Be careful not to cool down the gumbo. It is wise to add 1 vegetable and then wait 5 minutes, allowing the gumbo to heat back up before adding the next vegetable. Note the change in terminology: It’s now a gumbo that is still in its infancy. Cook, stirring occasionally, 30 minutes.

Add turkey pieces slowly so the gumbo does not cool down. Lightly boil, stirring occasionally, 30 minutes. Stir gently to avoid breaking up the turkey pieces.

Add seasonings and hot sauce. If your taste buds are sensitive to seasonings, add only half of each seasoning (except the garlic powder) and hot sauce.

With a small aluminum ladle, begin to remove grease from top of gumbo. If additional grease rises to the surface, remove before serving. (Removing the grease is a key step.) Taste the gumbo. If it still seems flat, cook it longer for a greater depth of flavor. The amount of heat under the gumbo and the number of times it is stirred either shortens or lengthens the process.

Once you have settled on the taste and the gumbo is ready for serving, add scallions and parsley. Serve over rice, making sure you do not see the rice in your bowl and removing bay leaves (if using). It’s not meant to be like a stew or rice and gravy. It should be served like a soup with rice at the bottom of the bowl.