Preheat oven to 425°.
Leave root and 1 inch stem on beets; scrub with a brush. Place beets on a baking sheet lined with foil. Bake at 425° for 45 minutes or until tender. Cool the beets slightly. Trim off beet roots; rub off skins. Slice each beet into 8 wedges.
Combine feta cheese and the next 6 ingredients (feta through pepper); stir well with a whisk.
Divide greens evenly among 4 plates, and top with beet wedges. Spoon dressing over salad. Sprinkle with onion and parsley.