Cut greens off where they meet the beets and save for later. Place the beets into a Dutch oven or other oven save container with a lid, such as a ceramic braiser.
Drizzle the beets with oil and rub with your hands to coat. Place the lid on the pot and place on the middle rack of the oven. Roast, covered, for 30-60 minutes.
Let the beets cool enough to handle. Slip the skins off with your fingers. Use a paring knife for any stubborn bits. Cut beets into rounds crosswise, dice, or cut into wedges.