Adjust an oven rack to the middle position and heat the oven to 400°F. Toss the sweet potatoes with oil, salt, and pepper on a rimmed baking sheet. Arrange the potatoes in a single layer and roast until the bottom edges are browned, about 25 to 30 minutes, flipping them halfway through the cooking time. Transfer the potatoes to a plate and let them cool for 20 minutes to prevent them from wilting the greens too aggressively.

Place the kale in a large bowl and vigorously squeeze and massage the leaves with your hands for about 1 minute. The leaves should look uniformly darkened and feel slightly wilted.

In a separate large bowl, whisk the water, pomegranate molasses, shallot, honey, vinegar, salt, and pepper until combined. Slowly drizzle in the oil while whisking constantly until the dressing is smooth and emulsified.

Add the cooled roasted potatoes, massaged kale, and radicchio to the vinaigrette. Toss gently to ensure every leaf is coated, then transfer to a serving platter. Garnish with pecans and shaved Parmesan to taste, and serve while the potatoes are still slightly warm.