1. To make the stock: Bring about a gallon (16 cups) of water (including oyster liquor, if available) to a light boil in a large pot. Add all of the remaining stock ingredients. Return to a bare simmer and cook for about 30 minutes. Strain the stock into another large pot and discard the solids.
2. To make the gumbo: Heat the oil in a large skillet until the oil shimmers. Add the okra and cook, stirring, for about 3 minutes. Remove the okra and set aside. Add the onions, bell pepper, celery, parsley, and oregano, and sauté until the vegetables are soft. Add the vegetables, including the okra, to the stock and bring to a simmer. Add the Creole seasoning.
3. Meanwhile, make the roux by melting the butter in a small saucepan over medium heat until it sizzles. Add the flour and whisk until it changes texture. Shift to a spoon and stir frequently until the roux reaches the desired color. For me, that would be the color of a pecan shell. Remove from the heat and stir in the sliced green onion. Keep stirring because the heat of the roux can still result in burning.
4. Whisk half of the roux into the gumbo. It will rise to the surface and appear not to blend in, but if you keep whisking, it will. Add some of the remaining roux until the color and consistency of the gumbo are the way you want.
5. Simmer the gumbo for about an hour. Season to taste with salt, pepper, and hot sauce. Just before serving, add the shrimp, crabmeat, crawfish tails, and/or oysters. Simmer 2-3 minutes, until the seafood is heated through. Serve with cooked long grain rice.