Peel and dice the sweet potatoes into bite-size pieces.
Put the potatoes into a large bowl and add the chili powder, cumin, and half of the olive oil. Stir well.
Cover the bottom of a baking pan with the other half of the olive oil. Add potatoes and place in oven. Cook for 20 minutes then stir and cook an additional 20 more minutes.
Cover potatoes with cilantro, sour cream, or other toppings of your choice.