Orange juice and tarragon season the dressing for this fresh side salad.
Thoroughly wash beets, but avoid using a brush because the beets have very thin skins. Cut off all but 1-inch of the stems and roots. Place the beets in a 2-quart baking dish. Drizzle with 2 tablespoons olive oil. Sprinkle with 1/2 teaspoon salt and 1/4 teaspoon black pepper. Roast, uncovered, in a 425 degree F oven for 55 to 60 minutes or till beets are tender. (A small knife or toothpick should slip in and out easily.) Let the beets stand until cool enough to handle, then peel the beets by slipping off the skins. (You want the beets to still be warm so the skins will come off easily.) Cut the beets into small wedges. Transfer beets to a medium bowl.
In a screw-top jar, combine 1/3 cup olive oil, orange juice concentrate, tarragon, 1/4 teaspoon salt and 1/8 teaspoon black pepper. Cover and shake well. Pour dressing over beets. Let stand for 20 minutes to allow beets to soak up flavor.
To serve, remove beets from dressing using a slotted spoon; reserve dressing. If you like, toss greens with reserved dressing. Divide greens among 6 salad plates; top with beet wedges. If you like, sprinkle each serving with nuts. Pass reserved dressing if you did not toss it with the greens. Garnish each serving with orange slices, if you like.