Arrange the beet chunks on a sheet pan, lined with parchment paper (optional for easy clean up). Drizzle the oil over the beets, and then use your hands to toss the beets in the oil.
Roast the beets, uncovered, for 30-35 minutes (depending on the size of the chunks), until soft when pierced with a fork.
Once the beets are cool enough to handle, place the beets in a storage containers. Pour the orange juice over the beets, and toss to coat the beets in the juice. The beets won't be fully submerged in the orange juice.
The beets will keep in the fridge, in an air-tight container, for up to a week. Use the beets to top on salads (try leafy greens and feta or goat cheese, and add some toasted nuts), or blended in smoothies (I use 2 chunks in a 2 serving smoothie).
*If you prefer not to peel and cut the beets then I recommend roasting them whole, particularly if the beets are on the smaller side. Simply wash the outside of the beets, place a piece of parchment under each beet (each sheet should be big enough to wrap around each beet), and drizzle the skin with a bit of oil. Wrap the beets in the parchment, and roast at 400F until soft when touched. Once cool, remove the parchment paper and peel the skin from the flesh. Cut the beets in half (presuming the beets are smaller).