Preheat oven to 350°F.
Remove the neck and giblets from your turkey, then rinse and pat it dry. Discard giblets and neck (see note).
Place sliced citrus and onion in the cavity of the turkey.
Whisk soy sauce, sherry, brown sugar and pepper together in a measuring cup.
Prepare the oven bag as directed on package (shake flour inside the bag and place the bag inside a roasting pan that is at least 2 inches deep).
Place the turkey in the bag. Pour the baste over the whole bird. (You do not need to salt the bird; the soy sauce does that for you.)
Seal the bag according to package directions and cut six 1/2 inch slits in the top of the bag.
According to the directions in the bag, the cooking time will be 1.5-2 hours for an 8-12 lb turkey, 2-2.5 hours for 12-16 lb turkeys, 2.5-3 hours for 16-20 lb turkeys, and 3-3.5 hours for 20-24 lb turkeys.
Cook turkey until the internal temperature reaches 180° in the thickest part of the thigh not touching the bone. Remove from oven and let stand in oven bag another 15 minutes.
While turkey is still in the pan, cut open the bag carefully and remove the turkey from the bag. Save the juices. Place on cutting board to rest until ready to carve.
Store leftover turkey in the refrigerator for 3 days. Freeze for up to 3 months.