Reserved neck, wing tips and giblets from the turkey
1 large onion, thickly sliced
1 large carrot, thickly sliced
1 large celery rib, thickly sliced
2 garlic cloves, sliced
1 teaspoon kosher salt
Freshly ground pepper
Preheat the oven to 400°. Put the whole turkey wings and the reserved wing tips in a flameproof roasting pan and roast for about 1 hour, turning occasionally, or until well browned. Transfer the turkey parts to a large pot.
Set the roasting pan over 2 burners. Add 1 cup of water and boil over moderately high heat, scraping up the browned bits from the bottom of the pan. Add the liquid to the pot.
Add the turkey neck, wing tips, gizzard and heart to the pot along with the onion, carrot, celery, garlic, salt, generous pinches of pepper and 8 cups of water. Bring to a boil over high heat. Reduce the heat to moderately low and simmer, partially covered, until the meat is falling off the bones and the gizzard is very tender, about 2 hours. Add the reserved liver and poach it in the stock until browned outside but still pink in the center, about 6 minutes.
Strain the stock. Reserve the liver, heart and gizzard for the gravy.
The stock and giblets can be refrigerated separately for up to 2 days. Skim the fat from the stock before using.