Leave root and 1-inch stem on beets; scrub with a brush. Place beets on a jelly-roll pan coated with cooking spray. Lightly coat beets with cooking spray. Bake at 400° for 45 minutes or until tender. Cool beets slightly. Trim off beet roots; rub off skins. Cut beets in half.
Combine orange juice and next 6 ingredients (through garlic) in a medium bowl, stirring with a whisk. Add beets, tossing gently to coat. Remove beets with a slotted spoon, and set aside, reserving orange juice mixture in bowl. Add salad greens and beet greens to bowl; toss well. Place about 1 cup greens mixture on each of 6 salad plates; top each with about 1 1/2 cups beets, 1/4 cup tangerine sections, 1 teaspoon cheese, and 1/2 teaspoon nuts. Serve immediately.