Wash turkey thoroughly and wipe dry.
Rub the entire surface as well as the cavity with salt and pepper and a few tablespoons of the lemon juice.
Scatter garlic over surface and tuck inside the cavity.
Place on a rack in a shallow roasting pan and insert meat thermometer in the thickest part of the thigh.
Roast in a 425° oven for 40 minutes; reduce temperature to 325° and roast until thermometer registers 175°, about 4 to 4 1/2 hours.
Sprinkle with oregano and pour remaining lemon juice over all.
Transfer to a carving board.
Pour 1/2 cup water into pan drippings and bring to a boil; skim fat and serve alongside.
Figure about 200 calories per 4 ounce serving.