Clean and peel the beets. Cut into 1-inch chunks (see note below on cooking times).
Toss the beets with a generous amount of balsamic vinegar and olive oil. You may need more than I’ve listed above.
Roast the beets at 375 for 30 to 60 minutes, until tender. The total cooking time depends on how big you chopped the beets. Pieces around 1/2-3/4 of an inch will probably cook in 30-40 minutes. Pieces around 1 inch will need closer to 60 minutes.
While the beets are still hot, toss them with some additional oil and vinegar and sprinkle with the feta cheese.