Preheat the oven to 400°F. Line a large rimmed baking sheet with parchment paper.
Place the sweet potatoes on the prepared baking sheet and rub them with the oil. Roast for 1 hour or until the sweet potatoes are very tender.
Meanwhile, in a large bowl, combine the salad greens, cherry tomatoes, walnuts, and carrots.
Remove the sweet potatoes from the oven and set aside for 5 minutes to cool. Peel the potatoes and cut into cubes.
In a small bowl, whisk the tahini, lemon juice, and water, if needed, to thin out the dressing. Season to taste with sea salt and pepper and drizzle over the salad mixture; toss to combine. Top with the sweet potatoes and serve immediately.