Preparation / Directions:
1) make seafood stock from shrimp carcasses or all of the above, substituting ham hocks, chicken backs, or necks, or other meats depending on availability. (For the 4 quarts of stock you will need about 4 pounds of shells, bones and meat.) Bring to a boil, lower heat and simmer several hours. Strain the stock, discarding solids. (If time is a factor, simmer shrimp heads and shells and ham hocks in chicken stock for at least an hour.)
2) Cook okra in the oil in a large, heavy pot over medium heat, stirring and scraping until some of the sliminess is gone; about 15 minutes. Add tomatoes, onions, celery, garlic, peppers, vinegar, the seasoning and herb mix and cook over low to medium heat for about 1/2 hour, stirring and scraping often.
3) Blend the roux into the okra and tomato mixture. Very slowly blend the stock into the mixture. Simmer about 1 hour.
4) Add crab and shrimp and simmer 10 to 15 minutes. Add oysters and simmer about 5 minutes. Add green onions. Serve over rice with file powder added to taste at the table. (File powder should not be cooked.)