Preheat the oven to 350 degrees F (175 degrees C). Brush some oil on the bottom of a glass or nonstick baking dish.

Peel sweet potatoes; cut into medium cubes.

Transfer sweet potato cubes to the baking dish. Add remaining oil, sprinkle with oregano, salt, and pepper, and toss to coat.

Bake in the preheated oven until sweet potato cubes are soft and fork-tender, 45 minutes to 1 hour.