Position oven racks in top and bottom thirds of oven. Preheat to 500F.
Bring a large pot of salted water to a boil. Cut potatoes into chunks. Add to boiling water. Boil until potatoes are slightly tender, about 10 min. Drain, then return potatoes to same pot. Cover pot and shake until potatoes are just fluffy on the outside. Drizzle oil over potatoes. Sprinkle with salt, then season with pepper. Shake to combine. Spread out in a single layer on two large baking sheets.
Roast in top and bottom thirds of oven, stirring potatoes and switching sheets halfway through, until potatoes are crispy and browned, about 25 min.