Step 1

To make the roux, heat the oven to 350 degrees. Heat the oil in a Dutch oven or in a heavy-bottomed, oven-proof skillet over high heat. Using a wire whisk or a wooden spoon, stir in the flour and continue to stir until flour and oil are well incorporated and there are no lumps. Transfer the skillet to the oven and cook, stirring every 30 minutes or so, until the roux reaches a deep brown color, about 2 hours.

Step 2

Remove the skillet from the oven and let cool; leave the oven on. When completely cool, pour off any excess oil. If making ahead, store the cooked roux in an airtight container at room temperature for up to 1 week.

Step 3

While the roux cools, spread the diced sausage on a baking sheet and bake it in the oven until the sausage is browned all over, about 20 minutes. Remove the sheet from the oven and use a slotted spoon to transfer andouille to a plate lined with paper towels to soak up any rendered fat. If making ahead, store the sausage in an airtight container in the refrigerator until ready to use, up to 3 days.

Step 4

When you’re ready to make the gumbo, heat the olive oil in a large pot or Dutch oven over medium-high heat. Add two-thirds each of the celery, onion and green bell pepper. Reduce the heat to medium and cook, stirring occasionally, until the onions begin to turn brown and caramelized, 15 to 20 minutes. Add the remaining celery, onion and bell pepper and cook, stirring occasionally, until the second addition of onions is translucent, about 5 minutes more. Stir in the filé powder (if using), the salt, cayenne, garlic and bay leaves, and cook, stirring often, until the filé loses its stringy quality, 2 to 3 minutes.

Step 5

Add the andouille and stock and bring to a boil over high heat. Reduce heat to maintain a steady simmer. Add the roux by the tablespoon, stirring to incorporate each addition before adding the next, until all the roux has been added. Reduce the heat to a bare simmer and cook, partially covered and stirring occasionally to prevent burning, for 1 hour. Skim off any fat that rises to the surface while the gumbo cooks.

Step 6

Add the turkey and continue to simmer, still partially covered, for 1 hour more. If you need more stock, add it 1 cup at a time. You want your gumbo to be brothy, but you don’t want to thin out your roux too much.

Step 7

Season the gumbo with black pepper then taste and adjust seasoning. Just before serving, stir in the parsley, green onion tops and lemon juice. Serve with rice.