Preheat the oven to 375°. In a baking dish, lightly drizzle the beets with olive oil. Season with salt and pepper. Cover with foil and roast until the beets are tender, about 45 minutes. Let cool, then peel the beets and cut them into julinne..in a large bowl, whisk the vinegar with the mustard. Whisk in the remaining 1/2 cup of oil until emulsified. Add carrot and season with salt and pepper; toss with the beets and walnuts. Transfer the beets to a platter, top with the apple and prunes and serve.
