Heat the oil in a large heavy pan and add the flour.
Cook over a low heat, stirring, to make a dark brown roux (the color of hazelnut shells).
Add the onion, garlic, green pepper and celery and cook until lightly browned, stirring occasionally.
Add the okra, parsley, bay leaf, thyme, salt, peppers, and cayenne and tabasco to taste, then stir in the tomatoes, tomato puree, and half the stock or water.
Bring to a boil, stirring well.
Simmer for 1-1/2 hours, stirring occasionally.
During this time, the okra, which is initially slimy, will turn the mixture very dark and glutinous.
Meanwhile, remove the chicken meat from the carcass.
Discard all skin and cut the meat into bite-sized pieces.
Add the chicken meat and corn to the gumbo with the remaining stock or water and simmer for 30 minutes longer, stirring from time to time.