Step 1: Roast the Beets and Sweet Potatoes

1. Preheat the oven to 400°F (200°C) and line a large baking sheet with parchment paper.
2. In a large bowl, toss the diced beets with 1 1/2 tablespoons of olive oil, a pinch of salt, pepper, and 1/2 teaspoon of garlic powder. Spread evenly on one half of the baking sheet.
3. In the same bowl, toss the sweet potatoes with the remaining olive oil, a pinch of salt, pepper, 1/2 teaspoon of garlic powder, and ground cumin. Spread evenly on the other half of the baking sheet.
4. Roast for 25-30 minutes, flipping halfway, until the vegetables are tender and caramelized. Remove from the oven and let them cool slightly.

Step 2: Prepare the Dressing

1. In a small mixing bowl, whisk together the Greek yogurt, tahini, lemon juice, olive oil, and honey until smooth and creamy.
2. Season with salt and black pepper to taste. Adjust the consistency by adding a bit of water if the dressing is too thick.

Step 3: Assemble the Salad

1. In a large salad bowl, combine the mixed greens and chopped mint leaves.
2. Add the roasted beets and sweet potatoes over the greens, followed by the crumbled feta, pomegranate seeds, and chopped roasted walnuts.

Step 4: Drizzle the Dressing

1. Just before serving, drizzle the creamy yogurt-tahini dressing over the salad.
2. Toss gently to ensure everything is evenly coated. Alternatively, serve the dressing on the side for a self-serve option.