Heat 1/2 cup vegetable oil over medium heat in a large pot, then whisk in 1/2 cup flour and stir constantly until the roux turns deep brown, about 15–20 minutes.

Add 1 large diced onion, 1 diced green bell pepper, 2 diced celery stalks, and 4 minced garlic cloves; sauté for 5 minutes until vegetables soften.

Stir in 1 pound sliced andouille sausage and cook for 5 minutes to release smoky flavors.

Add 1 pound diced chicken thighs and cook until no longer pink, about 5–7 minutes.

Pour in 8 cups chicken broth and add 2 cups sliced okra; bring the mixture to a gentle simmer.

Mix in 1 (14.5 oz) can diced tomatoes, 2 bay leaves, and 2 teaspoons Cajun seasoning; cover and simmer for 30 minutes.

Remove the lid, taste the gumbo, and season with salt and pepper to taste.

Discard bay leaves, ladle into bowls, and garnish with 4 sliced green onions and 1/4 cup chopped fresh parsley before serving.