Step 1: Heat 4 cups of turkey broth, chicken broth or water--or a combination of broth and water--in a saucepan until hot but not boiling.
Step 2: Transfer the cooked turkey from the roasting pan and set it on a cutting board to rest. Remove as much grease or fat as possible from the pan using a spoon, ladle or gravy separator. Reserve ¼ cup fat.
Step 3: Place the roasting pan over two burners on the stove on medium heat. Deglaze the pan by adding ½ cup water or other liquid (wine, turkey, or chicken stock). Stir constantly and scrape the bottom of the pan to loosen browned bits. Pour off the liquid from the roasting pan into a measuring cup or the saucepan of hot turkey broth.
Step 4: Add ¼ cup reserved fat to roasting pan over medium heat. Whisk in ¼ cup all-purpose flour. Cook gently, stirring constantly, until the flour loses its “raw” smell and the mixture becomes golden in color. Cooking the flour enhances the thickening power of the roux and adds color and nutty flavor to the gravy.
Step 5: Then transfer the roux to a saucepan. Whisk in the hot turkey broth and pan drippings and simmer over medium heat, stirring frequently, for 5 minutes or until thickened.
Step 6: Season to taste with salt and pepper. Transfer to a warmed gravy boat or serving bowl and garnish with fresh chopped sage. Other herbs and spices may suit your tastes as well; experiment with a pinch of cloves, a sprinkle of thyme, and a touch of mace.
Avoid the Lumps:
The trick to avoiding lumps is to cook together equal parts of flour with a fat, such as clarified butter, vegetable oil or grease. This mixture is known as a roux and serves as a thickener for gravy. As a general rule of thumb, a ½ cup of roux will thicken 4 cups of gravy. (See Making Roux for more information.)
Any type of liquid can be added to a roux to make gravy, including the broth or drippings from beef, pork or chicken. If you're roasting a turkey, use the drippings from the roasting pan and turkey broth to make the gravy.