
Preheat the oven to 390°F (200°C). Trim off the top of your beets and wrap them in foil. Once the oven is ready, roast the beets from 1 hour to 1 hour 15 minutes, or until they are tender. Cooking time will depend on their size.
After roasting the beets, let them cool and chill them in the refrigerator until you want to put together the salad.
When you are ready to prepare the salad, peel the oranges and cut into segments. Then peel and cut beets into thin slices.
Whisk together all ingredients to make the dressing. Taste and adjust to your liking. Toss the beets with about ⅓ of the dressing.
Place mixed greens on serving plates. Then arrange beet slices on top of the lettuce together with orange slices, mint, and roasted walnuts. Drizzle the remaining dressing and serve.