Preheat oven: Set oven to 400°F (200°C). Line a large baking sheet with parchment paper.
Season sweet potatoes: In a bowl, toss cubed sweet potatoes with 1 tablespoon olive oil, smoked paprika, cumin, salt, and pepper until evenly coated.
Roast: Spread seasoned sweet potatoes in a single layer on the prepared baking sheet. Roast for 20-25 minutes, flipping halfway through, until tender and lightly caramelized at the edges.
Prepare dressing: While sweet potatoes roast, whisk together olive oil, balsamic vinegar, Dijon mustard, maple syrup, minced garlic (if using), salt, and pepper in a small bowl. Set aside.
Massage kale: Place chopped kale in a large salad bowl. Drizzle with about half of the dressing and massage the kale with your hands for 1-2 minutes until it becomes darker in color, slightly wilted, and more tender. This breaks down the tough fibers and makes it easier to digest.
Combine salad: Add the warm roasted sweet potatoes, dried cranberries, and toasted walnuts to the massaged kale.
Dress and toss: Drizzle with remaining dressing and gently toss to combine all ingredients.
Garnish and serve: Top with crumbled goat cheese or feta if desired. Serve warm or at room temperature.