For the dark roux
1 cup corn, vegetable or safflower oil
1 cup all-purpose flour
1 medium onion, cut in small dice
2 stalks celery, cut in small dice
1 medium bell pepper, cut in small dice
10 cloves garlic, peeled and minced
For the turkey, dressing and gravy
1 12-pound turkey
2 pounds kosher salt
5 ribs celery, cut in medium dice
3 small onions, cut in medium dice
3 jalapeños, seeded and minced
2 bell peppers, cut in medium dice
1 medium head garlic, cloves peeled and minced
3 quarts water
3 bay leaves
5 tablespoons poultry seasoning
Kosher salt and freshly ground black pepper to taste
9 tablespoons (1 stick plus 1 tablespoon) butter
3 cups shucked oysters in their liquor
16 cups cubed crispy French bread (1-inch cubes)
4 medium eggs
2 cups chopped fresh parsley
2 scallions, thinly sliced
1 1/2 tablespoons chopped fresh rosemary
1/2 cup dark roux
To make roux, prepare a clean dry pot large enough so oil comes no more than a quarter of the way up the sides. Heat oil over high heat until it just starts to smoke. Add a third of the flour, stirring constantly with wooden spoon, for 30 seconds. Add another third of flour and stir for 30 seconds more or until well blended. Roux should be dark brown. Add remaining flour and stir for 30 to 45 seconds or until the roux is the color of milk chocolate.
Remove from heat, add onion and stir to incorporate thoroughly. Add celery and stir. Add bell pepper and garlic. Scrape bottom of pot. Let cool for 1 hour. Remove any excess fat that may rise to surface. Recipe yields 2 1/4 cups roux. (Roux will keep refrigerated in airtight container for two weeks. Use in gravy, gumbo or other Creole or Cajun dishes.)
For oyster dressing and gravy, wash neck and giblets thoroughly in cold water and place in large saucepan. Add half the celery, half the onions, half the jalapeños, half the bell peppers and half the garlic. Add 3 quarts cold water and bay leaves and season with salt and pepper. Bring to a boil and skim away foam. Stir in 3 tablespoons poultry seasoning. Reduce heat and simmer, skimming occasionally, for about 2 hours. Remove neck, pick off meat and dice it. Remove giblets, including liver, and dice and refrigerate for later use.
Preheat oven to 350F. Grease a piece of foil with 1 tablespoon butter. Place 4 tablespoons butter into large pot and melt over high heat until butter starts to smoke. Add remaining celery, onions, jalapeños, bell peppers, garlic and poultry seasoning, and cook over medium heat for 15 minutes, or until vegetables brown and become tender. Add oysters and their liquor and cook 4 to 5 minutes or until oysters' edges curl. Turn off heat, add half the bread and stir, soaking up any liquid. Add 1 cup unstrained stock and stir. Add remaining bread and stir. Add eggs, stirring constantly to be sure they don't cook when they hit hot mixture. Season with salt and pepper; add parsley, 1/2 tablespoon rosemary and scallions. Stuffing should be moist but pliable, damp but not wet. If it's too wet, add more bread; it it's too dry, add more liquid.
To prepare turkey, use one hand to separate breast skin from meat and place 4 tablespoons butter, cut into small pieces, between skin and meat, trying not to tear skin. Pat skin dry with towel and season bird inside and out with salt, pepper and 1/2 tablespoon rosemary.
Place turkey on rack in roasting pan. Tuck each wing tip under turkey. Stuff neck, pulling out skin and packing tightly. Stuff main cavity and tie ankles with butcher's twine. Cover cavity and breast with buttered foil (to protect breast and keep stuffing from burning), leaving legs, thighs and wings exposed. Add 1 quart stock and roast for 1 hour, basting exposed portions of turkey. Cook for 1 more hour, basting every 20 minutes. Remove foil, turn heat up to 375F and roast 1 hour more, or until center of stuffing reads 160F on an instant-read thermometer. Breast skin should be golden brown. Remove bird from oven and place on buttered platter, covered loosely with foil. Allow to rest at least 20 minutes.
Strain pan drippings into saucepot, and skim away excess fat. Place roasting pan over two stove burners, both on high heat. Add 3 cups stock to pan, and scrape bottom with wooden spoon. When liquid boils, remove and strain into saucepot containing drippings and bring mixture to a boil over high heat. Skim off any impurities. Whisk in 1/2 cup roux and return to a boil. Add giblets and remaining 1/2 tablespoon rosemary. Taste and season with salt and pepper if necessary. If gravy is too thick, add more liquid; if too thin, heat to reduce. Serve in gravy boat with turkey and dressing.