Preheat the oven to 375F. Wash the beets and place in a baking dish. Drizzle with 1 tablespoon of olive oil. Cover the dish with foil and bake for 45 to 60 minutes, until the tip of a knife can be inserted easily into the beets. Remove from the oven, allow to cool. Peel the beet skins and discard. Cut the beets into wedges. Whisk together the orange juice, the remaining 2 tablespoons olive oil and 1 tablespoon walnut oil, red wine vinegar, salt and pepper. Toss the lettuce with three quarters of the vinaigrette and place on a platter. Toss the beets with the remaining vinaigrette. Garnish the salad with the beets, orange sections and walnuts. Serve immediately.