Heat the butter in a large saucepan over medium heat until it bubbles. Add the parsley, green onions, celery, yellow onions, bell pepper and garlic. Cook the vegetables until the onions become translucent and the celery is no longer crunchy. Lower the heat to medium-low.
Put the poor boy bread cubes and all the crumbs into a large bowl. Sprinkle the oregano, sage, tarragon, filé, salt and pepper over the bread. Shake the bowl up and down a bit to make the cubes rise to the top. Put the cubes into the saucepan. Reserve the crumbs and small pieces.
Mix the oyster water, chicken stock, hot sauce and lemon juice. Add to the saucepan, wetting down the bread cubes. Stir the pan contents with a kitchen fork until the contents are equally moist throughout.
Add the oysters to the pan contents. Stir with a kitchen spoon only until distributed throughout. The less you stir, the better.
Stick a table knife into the pan mixture and move it sideways a couple of inches. If the resulting trench doesn't close most of the way in five seconds, stir in enough water so that it does. Simmer for three or four minutes. Taste the dressing and add salt, pepper, or hot sauce as needed.
Preheat the oven to 350 degrees. Spoon the dressing into a large casserole dish. Even off the top surface, but don't press it down to force out all the air gaps. The mixture should be fairly loose.
Sprinkle the reserved bread crumbs over the top of the stuffing. Bake for 30-40 minutes at 350 degrees, until the top is toasty and the center part of the stuffing is steaming hot. Keep it warm throughout dinner.