In a large heavy-bottomed pot or Dutch oven, heat the avocado oil over medium heat.
Add the sliced chicken andouille sausage and brown for 3-4 minutes until golden; remove the sausage and set aside.
In the same pot, sprinkle the cassava flour into the remaining oil and drippings, whisking constantly for 5-7 minutes until it turns a deep caramel color to form a clean roux.
Stir in the diced onion, green bell pepper, and celery (the holy trinity), sautéing for 5 minutes until softened.
Add the minced garlic, creole seasoning, sea salt, and black pepper, stirring for 1 minute until fragrant.
Slowly pour in the chicken broth while whisking to incorporate the roux, then add the sliced okra and the browned sausage back to the pot.
Bring the mixture to a gentle boil, then reduce heat and simmer for 15 minutes to allow the flavors to meld and the okra to thicken the broth.
Add the raw shrimp to the pot and cook for 3-4 minutes until they are pink and opaque.
Serve the gumbo hot over the portioned cooked brown rice.