Step 1: Roast the Sweet Potatoes and Beets

1. Preheat your oven to 400°F (200°C).
2. Line a baking sheet with parchment paper.
3. In a large bowl, toss the diced sweet potatoes and beets with 2 tablespoons of olive oil, salt, and pepper.
4. Spread the vegetables in a single layer on the prepared baking sheet.
5. Roast for 25-30 minutes, or until tender and slightly caramelized, turning halfway through the cooking time. Remove from the oven and allow to cool slightly.

Step 2: Prepare the Dressing

1. In a small mixing bowl, combine the olive oil, honey, Dijon mustard, apple cider vinegar, and lemon juice.
2. Whisk until the dressing is emulsified and smooth.
3. Season with salt and freshly ground black pepper to taste. Adjust the flavors as needed, adding more honey for sweetness or mustard for a sharper kick.

Step 3: Assemble the Salad

1. In a large salad bowl, arrange the mixed greens as the base layer.
2. Scatter the roasted sweet potatoes and beets over the greens.
3. Add the thinly sliced apples, crumbled feta cheese (if using), dried cranberries, and toasted walnut halves.

Step 4: Dress the Salad

1. Drizzle the Honey Dijon dressing over the salad.
2. Toss gently to ensure all the ingredients are well coated.

Step 5: Serve and Enjoy

1. Transfer the salad to a serving platter or individual plates.
2. Serve immediately while the roasted vegetables are still warm, or chill for a cool, refreshing version.