1. In a large pot over medium-heat, add 1 tablespoon of the ghee or butter, the onion, celery, bell pepper, and garlic. Cook for 8 minutes, stirring occasionally. Add the tomatoes, cayenne, thyme, sea salt, black pepper, gumbo filé, and bay leaf. Stir and let cook for 5 minutes.
2. In a small saucepan over medium heat, add 2 tablespoons ghee or butter and ½ cup of the shrimp stock. Cook for 5 minutes, stirring frequently. Slowly whisk in the arrowroot powder to make a roux and cook, stirring constantly, for 5 minutes as it thickens. Slowly whisk in 1 cup of the shrimp stock and let simmer over medium heat, stirring frequently, and cook for 5 minutes more.
3. Add 2 cups of the shrimp stock to the large pot, increase the heat to medium-high, and slowly stir in the roux until fully incorporated. Bring to a boil, then reduce to a simmer.
4. Cook for 5 minutes, or until thickened, then remove from the heat and add the shrimp.
5. In a sauté pan over medium-high heat, cook the andouille sausage in the remaining 1 tablespoon ghee or butter until browned, about 5 minutes per side. Deglaze the pan with the remaining ½ cup shrimp stock, then transfer the sausage and drippings to the large pot and stir in. Remove and discard the bay leaf.
Serve the gumbo immediately as is, or spoon over cauliflower rice. Garnish with the chopped scallions.
Store leftovers in an airtight container, refrigerated, for up to 1 week.