01 - Preheat the oven to 400°F. Line a large baking sheet with parchment paper.
02 - In a bowl, toss the beets and sweet potatoes with 2 tbsp olive oil, 1/2 tsp sea salt, and 1/4 tsp black pepper. Spread evenly on the prepared baking sheet.
03 - Roast for 35–40 minutes, tossing halfway, until golden and tender. Let cool slightly.
04 - While vegetables roast, whisk together the Greek yogurt, olive oil, lemon juice, honey, Dijon mustard, garlic, salt, and pepper in a small bowl. Adjust seasoning to taste.
05 - Arrange the arugula or mixed greens on a large serving platter. Top with the roasted beets, sweet potatoes, and red onion.
06 - Drizzle with the creamy yogurt dressing. Sprinkle crumbled feta and toasted walnuts or pecans on top.
07 - Serve immediately, or chill for up to 1 hour before serving.