1. Preheat oven to 350°.
2. Place duck in a roasting pan, and season with salt and pepper.
3. Roast until tender, about 1 hour for legs or 2 hours for the whole duck. If desired, reserve rendered duck fat to make the roux. Let the duck cool, and pick the meat off the bones. Alternatively, duck can be smoked.
4. In a large cast-iron Dutch oven, heat ½ cup oil (or reserved duck fat) over medium-high heat until almost smoking. Add flour; cook, whisking constantly until the roux turns a deep brown, add onion, celery, and bell pepper; reduce heat to medium, and cook for 5 minutes, stirring frequently. Stir in sausage, and cook for 3 minutes; stir in garlic. Whisk in stock, 1 cup at a time; bring to a boil. Reduce heat, and simmer for 15 minutes.
5. In a small skillet, heat the remaining 2 tablespoons of oil (or rendered duck fat) over medium-high heat. When oil is hot but not smoking, sear okra, and add to pot along with the green onion. Add duck meat, Worcestershire, thyme, filé powder (if using), bouquet garni, hot sauce, and a little salt. Simmer over low heat for at least 1 hour, stirring occasionally.
6. Skim off any fat from the top. Season with salt, pepper, and hot sauce. Serve with hot cooked rice, if desired. Garnish with green onion, if desired.