In a large heavy pot coated with 1 tablespoon oil, saute' chicken and sausage on medium high heat until brown on all sides. Some of the meat will stick to the bottom of the pot then release. The crust that forms is called "gratin". This is one of the secrets of Cajun cooking that adds a rich flavor and is an important step in making an authentic New Orleans gumbo recipe. Remove and set aside.
Cut up onions, celery, and green pepper and set aside covered.
Place oil and flour in pot, stir well and brown to make a roux. When flour is browned to the color of milk chocolate or an old copper penny, add chopped vegetables and saute on low heat for 8-10 minutes.
Gradually add chicken stock stirring constantly until blended.
Add chicken and sausage and all other ingredients except the shrimp, okra and parsley which will be saved for the end.
Cover and simmer on low heat for 30 minutes. Remove lid and cook 30 more minutes stirring occasionally.
Add shrimp, okra and parsley and continue to cook on low heat uncovered for 15 minutes.
Serve in gumbo bowls or soup dishes of your choice. I prefer the gumbo bowls from Tabasco as they have the right depth, size and beauty for Authentic New Orleans Gumbo. A serving of 1/3 cup rice to 1 1/4 cup gumbo is the way it's done in New Orleans.