Cut carrots, cucumber, and mango into matchsticks. Finely chop nuts, cilantro, and mint. Lay spinach leaves on a flat work surface. Arrange carrots, cucumber, mango, and bean sprouts on each leaf. Top with nuts, then cilantro and mint. Roll up and tie with a blanched chive or green onion. Trim ends to shape. Hold each roll upright and pour about 1 teaspoon sauce into each (or use as a dipping sauce). Serve, passing extra sauce.