To roast the sweet potato, preheat the oven to 425 degrees F. Cut the potato in half lengthwise and brush the flesh with 1 tablespoon olive oil. Place flesh-side down on a rimmed baking sheet and roast until the potato can easily be poked with a fork, about 40 minutes. Spoon the flesh into a small bowl and refrigerate until chilled, about 1 hour and up to overnight. Discard the skins.