Put the meat, if using, with the salt, cayenne, and bay leaves in a large deep pot and add water. Bring to a boil over medium-high heat and cook for 30 minutes. With a slotted spoon, remove the meat and chop it. Set aside.
Reduce the heat to medium and add the greens, a handful at a time, and blanch until they are wilted. Drain, reserving the liquid. Coarsely chop the greens. Set aside.
In the same pot, heat the oil over medium heat and add the onions, bell peppers, and celery. Cook, stirring often, until the vegetables are wilted and golden, about 10 minutes.
Add the meat, greens, reserved liquid, thyme, oregano, basil, and parsley. Bring to a gentle boil and simmer for 1 1/2 hours. Remove the bay leaves. If not using meat, add 4 tablespoons butter to the pot just before removing from the heat.
Serve in deep soup bowls with filé powder passed at the table for guests to thicken the gumbo to their personal taste.
Yield: 8 to 10 servings