Heat oven to 350.
Remove the stem, seeds and membrane from each pepper. Wash inside and out. Cook peppers in boiling salted water 5 minutes; drain.
Cook and stir ground beef (or turkey) and onion in large skillet until onion is tender. Drain off fat. Stir in salt, garlic salt, rice and 1 cup of the tomato sauce; heat through.
Lightly stuff each pepper with approximately 1/2 cup meat mixture. Stand peppers upright in ungreased baking dish. Pour remaining tomato sauce over peppers.
Cover and bake 45 minutes. Uncover and bake 15 minutes longer.
Add sliced provolone cheese (optional) and serve.