3. Place sweet potato slices on prepared baking sheet. Brush a very thin layer of olive oil onto each side of the sweet potato. Bake for 20 minutes. Flip each sweet potato slice over, and bake for another 10 minutes. If you like it a little more toasted – leave in for an additional 5 minutes. {Note: You can also simply place the slices in a traditional toaster. Toast on high for 2-3 cycles or until toasted).