Prepare the roux: In a large pot or Dutch oven, heat the vegetable oil over medium heat. Gradually whisk in the flour. Cook, stirring constantly, until the roux turns a dark chocolate color (about 20-30 minutes). Be careful not to burn it.

Sauté the vegetables: Add the diced onion, bell pepper, and celery (the 'holy trinity') to the roux. Cook for 5-7 minutes until softened. Stir in the minced garlic and cook for another minute.

Brown the meats: Push the vegetables to one side and add the chicken thighs. Brown on both sides, then add the sliced sausage. Cook for another 2-3 minutes.

Add liquids and seasonings: Pour in the chicken stock and diced tomatoes. Add the bay leaves, thyme, paprika, cayenne, salt, and black pepper. Stir well to combine.

Simmer the gumbo: Bring to a boil, then reduce heat to low. Cover and simmer for 1 hour, stirring occasionally.

Add okra: Stir in the sliced okra and continue simmering uncovered for another 30 minutes. The gumbo should thicken slightly.

Adjust seasoning: Taste and adjust salt, pepper, or spices as needed. Remove bay leaves before serving.

Serve: Ladle the gumbo over cooked white rice in bowls. Garnish with chopped fresh parsley.