Preheat the oven to 400°F (200°C). Wrap each beet in aluminum foil and arrange them on a baking sheet. Roast for 45-60 minutes until they're fork-tender.

Cool the beets slightly, then peel off the skins using gloves. Slice the beets into bite-sized pieces.

Wash the mixed greens thoroughly and place them in a large salad bowl.

Whisk together olive oil, balsamic vinegar, honey, salt, and pepper in a small bowl until it emulsifies.

Toss the sliced beets over the greens with crumbled feta cheese and toasted walnuts. Drizzle the dressing over the salad.

Serve immediately on individual plates or from the bowl.