Using paper towels, pat turkey dry inside the cavity and all over the outside. The drier it is, the crispier the skin will be.
In a small mixing bowl, combine all the dry rub ingredients and stir. Starting with the back, press and rub about ¼ of the mixture into the skin. Flip the bird breast side up and rub another quarter of the rub in the cavity. Press and rub the remaining dry rub all over the sides and top of the breast, and all over the thighs. If a great deal has fallen into the pan, carefully scoop it up and press it back onto the bird.
While turkey comes to room temperature, take the rack out of the roasting pan, setting turkey on a rimmed baking sheet. Clean and dry the roasting pan – the juices accumulated overnight will make the pan dripping gravy much too salty.
To the clean, dry roasting pan bottom, add 1 quartered onion, the garlic, carrots, and celery. Set the turkey back into the roasting pan. Push a mix of onions and oranges into the cavity. Set remaining onions and 2 orange wedges in the bottom of the roasting pan. To truss the turkey wrap cotton twine around the breast of the bird to tie the wings close to the sides. Tie the drumsticks together. Finally, brush the turkey all over with the olive oil and add the white wine to the bottom of the pan.
Roast 20 - 40 minutes, or until the bird is nice and golden. Turn heat down to 350 degrees F, and cook the turkey until the internal temperature (measured by a thermometer inserted where the thigh meets the breast and again in the thickest part of the breast) hits 165 degrees F. I like to check the turkey every half hour, but there's no need to take the temperature until the 2 hour mark. If the breast or wings start to brown too much, add a foil tent over the turkey. Refrain from basting the bird – the skin will crisp and brown perfectly just as it is.
When the internal temp is at 165 degrees F, after about 3 - 4 hours total, set the bird on a carving board and rest, tented with foil, for 30 minutes.
Meanwhile set the roasting pan over 1 - 2 burners on medium heat, use a slotted spoon to remove the aromatics, vegetables, and oranges. Whisk the flour into the drippings. Once the mixture has thickened, still whisking, slowly add the stock, allowing mixture to thicken between additions. Edge heat lower, if needed. Continue cooking and whisking until all the stock has been added. If desired, scrape gravy into a smaller pan and keep over the lowest possible flame until it’s time to serve.