Comment by anvil-on-my-toe

If you're a slave in antebellum North Carolina, you have rosin on-hand and an open fire, no oven. You can cook your potatoes on the hot coals and ash or boil them in water in a pot. This method might have been more thermally efficient than either of those options and resulted in a nicer inner texture, while also conveniently sealing the cooked potato in a waxy later so it could be consumed later.