You bake sweet potatoes in the oven by washing the tubers thoroughly, piercing the skin several times with a fork, and placing them on a baking sheet. Bake them at four hundred degrees Fahrenheit for forty five to sixty minutes until the flesh feels completely soft and tender. Piercing the skin allows steam to escape safely during the baking process without bursting the potato. Let them cool slightly before slicing open and serving with your favorite toppings.