Preheat the oven to 400°F (200°C). Wash the beets thoroughly, then wrap each beet individually in aluminum foil.

Place the wrapped beets on a baking sheet and roast for 45 minutes, or until tender when pierced with a fork.

Let the beets cool slightly, then peel and slice them into thin rounds or wedges.

In a small bowl, whisk together olive oil, balsamic vinegar, honey, Dijon mustard, salt, and pepper to make the dressing.

Arrange the mixed greens on a serving platter. Top with sliced beets, crumbled goat cheese, and chopped walnuts.

Drizzle the dressing over the salad just before serving. Toss lightly if desired.