After the turkey is removed from the roasting pan, strain the liquid into a pot.
On medium high heat, bring the turkey drippings to a boil. (I usually have a few cups of liquid in my pot.)
In a small bowl or cup, add the cornstarch. Pour in water and stir with a fork until you have a smooth liquid.
With a whisk, slowly pour ⅓ of the cornstarch mixture into the pot of boiling drippings. Whisk as it thickens. Continue to pour increments of cornstarch mixture to your pot of gravy, until you have reached your desired thickness.
Reduce to medium low. Add the tamari and salt and pepper to taste.