Preheat your oven to 400°F (200°C). Wash the beets and wrap each in aluminum foil. Roast for 45 to 60 minutes until tender. Let cool, then peel and dice.

In a large bowl, add spinach and toss in the diced roasted beets, mandarin oranges, and sliced red onion.

In a small bowl, whisk together olive oil, balsamic vinegar, salt, and pepper until emulsified.

Drizzle the dressing over the salad and toss gently to coat.

Top with toasted pine nuts and crumbled feta cheese. Serve immediately or chill for 30 minutes before serving.