Preheat your oven to 425°F (218°C).

Spread the all-purpose flour evenly in a cast iron skillet.

Transfer to the preheated oven and toast for 15 minutes, stirring occasionally, until it reaches a deep cinnamon color.

Remove from the oven and transfer to a bowl.

Whisk in 1 cup of chicken stock to form a smooth mixture. Set aside.

In a Dutch oven, heat 3 tablespoons of vegetable oil over medium-high heat.

Add celery, bell pepper, onion, and jalapeño, then sauté until soft and translucent (about 5 minutes).

Stir in garlic and sliced andouille sausage, then cook for another 2 minutes.

Stir in the toasted flour mixture (roux) and cook for 2 more minutes, stirring constantly.

Pour in the remaining 5 cups of chicken stock and bring the mixture to a boil.

Add salt, black pepper, cayenne pepper, gumbo filé, thyme, and bay leaves.

Mix well, then reduce heat to low, cover, and simmer for 30 minutes.

After 30 minutes, add the shrimp, cover, and cook for an additional 10 minutes until shrimp is pink and fully cooked.

Remove bay leaves, then ladle the gumbo into bowls.

Serve hot over white rice, garnished with fresh parsley or green onions.