How to Make It
Preheat the oven to 350°. Wrap the beets in foil and roast for about 1 1/4 hours, or until tender. Let cool, then peel the beets and cut them into 1/4-inch dice.
In a bowl, whisk together the orange juice, zest, honey, vinegar, mustard and oil; season with salt and pepper. Add the beets and toss to coat. Arrange the salad greens on a large plate and top with the beets and red onion.