After your turkey is done cooking, carefully remove all the liquid pan drippings from the bottom of the roasting pan. Pour it through a fine mesh metal strainer.
Let the turkey drippings sit for a few minutes until the fat floats to the surface. Remove most of the fat as you can with a ladle and discard it. (I like to leave a little bit to add flavor.)
Measure 2 1/4 cups of drippings, adding water or chicken broth if you don't have enough liquid.
Into a heavy medium saucepan, pour about 1/2 - 3/4 cup of the drippings. Add the flour and whisk vigorously until smooth.
Cook the mixture over medium heat, whisking constantly until it gets thick and starts to turn golden brown. (This is your roux.)
Gradually whisk in the remaining liquid, then cook and stir over medium heat for 7-10 minutes, or until the gravy is your desired thickness.
Whisk in the pepper and soy sauce. Taste and add additional salt and pepper if needed.
Pour into a gravy boat and serve over mashed potatoes, roasted turkey, or stuffing.
Leftover turkey gravy can be stored in the refrigerator for 4-5 days. When you reheat it, you may need to add additional liquid.