Preheat oven to 350 degrees F (175 degrees C). Coat the bottom of a glass or non-stick baking dish with olive oil, just enough to coat.
Wash and peel the sweet potatoes. Cut them into medium size pieces. Place the cut sweet potatoes in the baking dish and turn them so that they are coated with the olive oil. Sprinkle moderately with oregano, and salt and pepper (to taste).
Bake in a preheated 350 degrees F (175 degrees C) oven for 60 minutes or until soft.