Bring the stock to a gentle simmer in a separate pot and keep warm.
Heat the oil, lard, or bacon fat in a large Dutch oven over medium high heat. Gradually whisk in the flour.
Cook the roux, stirring frequently, until it reaches a deep chocolate brown, about 15 to 25 minutes. Watch carefully to prevent it from burning.
Add the bell pepper, onions, celery, and garlic. Cook, stirring often, for 6 to 8 minutes, until the vegetables have softened.
In a small bowl, combine the black pepper, paprika, cayenne, thyme, oregano, garlic powder, and celery seed.
Gradually ladle the warm stock into the roux, stirring well after each addition until incorporated.
Bring the gumbo to a strong simmer. Add about half of the seasoning mixture and the venison. Taste and add additional seasoning and salt as desired.
Reduce the heat to a gentle simmer, cover, and cook for 1½ to 3 hours, or until the venison is very tender.
If using bone in venison, remove the meat once tender and allow it to cool enough to handle. Remove the meat from the bones and return it to the gumbo.
Add the sliced andouille and simmer for another 15 minutes.
Stir in the filé powder, sliced green onions, and chopped parsley. Cook for 3 minutes more.
