Heat oil in pot over medium heat.
Whisk flour slowly into hot oil.
Stir until roux turns dark brown.
Add onion, pepper, and celery.
Cook until vegetables soften well.
Add garlic and stir briefly.
Add sausage and chicken pieces.
Stir until lightly browned.
Pour in chicken broth gradually.
Add spices and bay leaves.
Simmer gently for forty minutes.
Stir occasionally to prevent sticking.
Remove bay leaves before serving.
Serve gumbo over warm rice.