Mix the salt, pepper and sage in a bowl and set aside.
Unwrap the turkey, pat dry with paper towels and place on a cutting board. Loosen the skin with your hands.
Place 1/4 of the salt and sage mixture evenly under each breast, spreading it out as far as you can. Sprinkle half of the remaining salt on the skin and rub in.
Turn the turkey over and sprinkle in the remaining salt.
Ball up four or five pieces of foil in a roasting pan. Place the turkey on top, breast side up (you can roast it upside down if you want to) and place uncovered in the fridge for 8 hours or up to 24 hours if you have that much time.
When you are ready to bake, preheat the oven to 450. Stuff the cavity of your turkey with the carrot, celery, onion, and lemon. No need to peel them.
Place the turkey back on the foil balls and roast uncovered one hour. Turn the oven down to 350 and roast 30 minutes, then check the temperature of your turkey making sure not to touch the bone. Roast until the turkey reaches 160.
Remove from the oven, cover with foil and allow to rest on the counter for 15 to 20 minutes before slicing (temperature of the turkey will rise while it rests).
You can throw away the vegetables in the cavity if you choose, then slice your turkey and serve warm.