Preheat an outdoor grill or bring a campfire to medium heat (325 degrees F to 375 degrees F).

Mix together salt, Italian seasoning, pepper, and garlic powder in a bowl. Pierce potatoes in several places with tines of a fork. Rub about 1 1/2 teaspoons oil onto each potato, then rub evenly with spice mixture. Put each potato onto a 12x12-inch sheet of heavy-duty foil. Wrap foil around potatoes and seal edges tightly, then wrap each packet with another sheet of foil.

Grill packets, or nestle them into hot embers, rotating every 5 minutes, until potato flesh is soft, about 25 minutes total. (Carefully open 1 packet to check doneness with a fork. The potato's skin crisps during cooking, so you can't tell just by squeezing it.) Let rest 10 minutes before opening. Serve with your favorite toppings.

To cook it indoors: Preheat oven to 400 degrees F. Prepare packets (skip the extra layer of foil) and transfer to a baking sheet. Roast until potatoes are softened, about 45 minutes. Let rest 10 minutes before opening.