In a large pot, combine the vegetable oil and flour over medium heat. Stir constantly until the mixture turns a dark brown color, resembling chocolate, about 20 to 30 minutes.

Add the diced onion, bell pepper, and celery to the roux. Cook for about 5 minutes until the vegetables soften and the mixture becomes aromatic.

Stir in the minced garlic and sliced sausage. Sauté for another 3 to 5 minutes until the sausage is slightly browned.

Add the cubed chicken thighs to the pot. Cook, stirring occasionally, until the chicken is no longer pink, around 5 to 7 minutes.

Stir in the diced tomatoes with their juice and chicken broth, scraping up any brown bits from the pot for added flavor.

Add the okra, Cajun seasoning, dried thyme, and bay leaves. Bring the mixture to a boil, then reduce to a simmer and cover.

Let the gumbo simmer for at least 1 hour, stirring occasionally.

Remove the bay leaves and adjust seasoning with salt and pepper to taste. Serve over cooked white rice and garnish with chopped green onions and parsley.