Combine the oil and flour in a large cast-iron pot or enameled cast-iron Dutch oven, over medium heat. Stirring slowly and constantly for 20 to 25 minutes, make a dark brown roux, the color of chocolate.
Season the onions, bell peppers, and celery with the salt and cayenne. Add this to the roux and stir until soft, about 5 minutes. Add the sausage and cook, stirring often, for 5 minutes. Add the broth and bring to a boil. Reduce the heat to medium-low and simmer, uncovered, for 45 minutes. Add the reserved turkey meat and the reserved onions and celery and cook for 15 minutes. Add the parsley and green onions.
Serve in soup bowls with rice. (FilÈ powder can be added at the table according to personal taste.)
Yield: 8 servings