Roasted Sweet Potato and Black Bean Salad

2       large sweet potatoes (about 1½ pounds), peeled and cut into 1-inch pieces
1       teaspoon sea salt, divided
1/2    teaspoon freshly ground black pepper, divided
1/4    cup fresh lime juice, plus wedges for garnish
1       tablespoon raw apple cider vinegar
1       tablespoon finely chopped garlic
1       can (15 ounces) black beans, rinsed and drained
1       cup halved heirloom cherry tomatoes
1/2    cup thinly-sliced orange or red bell pepper
1/2    cup thinly-sliced scallions
1/3    cup chopped fresh mint
4       cups baby arugula
coconut oil cooking spray

Heat oven to 375 degrees. On a baking sheet coated with coconut oil cooking spray, place potatoes in a single layer. Sprinkle with ½ teaspoon salt and ¼ teaspoon pepper. Bake until tender, about 15 minutes; let cool. In a small bowl, whisk lime juice, vinegar, garlic, ½ teaspoon salt, and ¼ teaspoon pepper. In a large bowl, combine potatoes, beans, tomatoes, bell pepper, scallions, and mint; toss with vinaigrette. Serve over arugula and garnish with lime wedges.