Preheat the oven to 400 F. Wash the beets, and wash and trim the greens.
Cube the beets and tofu, chop the onion. Put the beets, onions and tofu in a large, deep roasting pan. Add the thyme, olive oil, salt and pepper. Toss to coat.
Cover with foil and roast for 45 minutes.
Uncover, stir in beet greens, then cover and let steam until tender
Uncover and drizzle with balsamic vinegar. Season with more salt and pepper, and toss to mix. Transfer to a serving platter.