In a small bowl, combine all the chicken seasoning ingredients. Set aside.
1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon paprika, ½ teaspoon dried basil, ½ teaspoon dried oregano, ½ teaspoon dried thyme, ½ teaspoon salt, ½ teaspoon black pepper, ½ teaspoon cayenne pepper, 1 teaspoon olive oil
Pat the chicken thighs dry with paper towels. Season both sides generously with the spice mixture, pressing it into the meat.
Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add the sliced andouille sausage and cook until browned and slightly crispy. Remove to a plate and set aside.
1 pound andouille sausage
In the same pot, add the seasoned chicken thighs. Sear on both sides until golden brown, about 3 to 4 minutes per side. The chicken does not need to be fully cooked at this stage. Transfer to the plate with the sausage.
1 pound bone-in chicken thighs
Reduce heat to medium. Add the vegetable oil to the pot, then whisk in the flour. Cook the roux, stirring constantly, until it reaches a deep chocolate-brown color, about 10 to 15 minutes. Do not stop stirring to prevent burning.
½ cup all-purpose flour, ½ cup vegetable oil or avocado oil
Stir in the chopped onion, green bell pepper, red bell pepper, and celery. Cook for 4 to 5 minutes, until the vegetables are softened. Add the minced garlic and cook for 30 seconds, until fragrant.
1 cup yellow onion, ½ cup green bell pepper, ½ cup red bell pepper, ½ cup celery, 3 cloves garlic
Gradually pour in the warm chicken broth, stirring constantly to fully incorporate the roux. Add the bay leaf and bring the mixture to a gentle boil.
3 cups chicken broth, 1 bay leaf
Return the chicken thighs to the pot. Reduce the heat to low and simmer uncovered for 40 to 45 minutes, until the chicken is tender and fully cooked.
Remove the chicken from the pot. Discard the bones and shred the meat into bite-sized pieces.
Return the shredded chicken and cooked sausage to the pot. Stir in half of the chopped parsley and all of the green onions. Simmer for an additional 10 minutes to allow the flavors to meld.
¼ cup fresh parsley, ½ cup green onions
Taste and adjust seasoning with salt, black pepper, and Cajun seasoning as needed. Remove and discard the bay leaf.
Salt
Serve the gumbo hot over cooked white rice. Garnish with the remaining parsley and extra green onions, if desired.
Cooked white rice