Heat the oil in a large pot over medium-high heat. Add the onion, celery, and bell peppers and cook until softened, about 5 minutes.
Reduce the heat to medium and sprinkle the flour over the vegetables. Stir until the flour is thoroughly combined and beginning to brown, about 2 minutes.
Slowly pour in the chicken broth, whisking constantly to avoid lumps. Bring to a boil, then reduce to a simmer.
Add the chicken, thyme, oregano, garlic powder, bay leaves, cayenne pepper, black pepper, and salt. Simmer for 45 minutes, stirring occasionally.
Add the parsley and green onions and simmer for an additional 15 minutes. Taste and adjust the seasoning if needed.
Serve hot with cooked white rice.
Interesting Facts
Gumbo is a classic Creole dish from Louisiana.
Gumbo is traditionally served over cooked white rice.
The key to a good gumbo is a flavorful roux.
Gumbo can be made with a variety of proteins, such as chicken, shrimp, or sausage.