Chicken, Shrimp, and Sausage Gumbo Hazel

MAKES 10 TO 12 MAIN-COURSE SERVINGS. Combine the seasoning mix ingredients thoroughly in a small bowl. Makes 5 tablespoons plus 3/4 teaspoon. Sprinkle the chicken pieces all over with 1 tablespoon of the seasoning mix and rub it in well with your hands. Heat the oil in a 12-inch skillet (preferably cast iron) over high heat. When the oil begins to smoke; add the chicken skin side down, starting with the larger pieces, and cook, turning once, just until golden brown on both sides, about 4 to 5 minutes. Leave the thighs in longest, as they have the most fat to be rendered. Remove the chicken from the skillet and drain on paper towels. Add the sausage to the oil in the skillet and cook, turning once, until browned, about 4 minutes. Remove the sausage and drain on paper towels. Pour 3/4 cup of fat from the skillet into a measuring cup and discard the rest. Place the skillet over high heat until hot, about 30 seconds. Add the reserved fat and heat until hot, about 1 minute. Add the flour l/4 cup at a time, whipping constantly with a wire whisk until all of the flour is absorbed and the mixture has become, a light chocolate-colored roux. Quickly stir in 2 cups of the onions, 1 cup of the bell peppers, and the celery. Add 2 tablespoons of the seasoning mix, the parsley, and bay leaves and cook, stirring, until the roux is thick and dark chocolate-colored, about 3 to 4 minutes. Bring the seafood and chicken stocks to a boil in a heavy 8-quart pot over high heat. When the stock is boiling, add the roux in 2 installments, whisking until the roux has thoroughly dissolved into the stock. Bring the mixture back to a hard boil, whisking often to ensure that the flour doesn't separate and burn, about 9 to 11 minutes. Scrape the bottom of the pot frequently with the whisk to be sure that the flour isn't sticking. Add the browned chicken and sausage, the remaining seasoning mix, and the remaining 1 cup each onions and bell peppers. Stir well, cover, and bring to a boil. Reduce the heat to low and simmer until the chicken is tender, about 45 minutes. Remove from the heat, stir in the shrimp, cover, and let sit 10 minutes. Makes about 12 cups. Serve in shallow bowls over rice or potato salad.