To thicken the stock into gravy, the formula is 2 tablespoons each of fat and flour per cup of liquid — a quart of stock (4 cups) needs ½ cup (one stick) of butter and ½ cup of flour (preferably Wondra, “instant” flour that helps prevent lumps).
Flour tastes raw unless you cook it both before and after you add liquid. So melt the fat in a saucepan, add the flour, and cook this roux several minutes. Heat the stock to roughly the same temperature as the roux and mix it in, stirring well and constantly as you do. A flat whisk gets into the corners of the saucepan where the roux tends to stick.
Let the gravy boil, then simmer for at least as many minutes as you added tablespoons of flour. Season it, chill it. Tomorrow, you’ll deglaze the roasting pan and pour the gravy into the drippings to heat.
Make-Ahead Turkey Gravy
Start to finish: 4 hours (30 minutes active); Servings: 8
For the stock:
The giblets, neck and wing tips from 1 turkey
4 cups low-sodium chicken broth or water
1 small yellow onion, coarsely chopped
1 small carrot, halved lengthwise
1 celery rib, halved lengthwise
1 small parsnip, halved lengthwise
1 sprig fresh thyme
1 sprig fresh parsley
1 bay leaf
1 teaspoon whole black peppercorns
For the gravy:
1/2 cup turkey fat (skimmed from the stock) or butter
1/3 cup Wondra or all-purpose flour
Salt and ground black pepper
1 cup dry white wine or chicken broth (optional)
For the stock:In a small to medium saucepan over medium-high, combine the giblets, neck and wing tips with the broth. Bring to a boil, then immediately reduce to a simmer, skimming off the scum that rises to the surface. After about 20 minutes, when no more is scum rising, add the onion, carrot, celery, parsnip, thyme, parsley, bay leaf and peppercorns. Return to a simmer and cook, adding water as needed to maintain the level, for 3 to 4 hours. Set aside to cool. Once cooled, skim off and reserve any fat. Strain the stock and set aside; discard the solids.