1) Rinse quinoa under cold water. In a medium pot, combine quinoa and water. Bring to a boil, reduce heat, cover, and simmer for 15 minutes. Fluff with a fork and let cool.
2) In a large bowl, combine cooked quinoa, black beans, mango, bell pepper, red onion, and cilantro.
3) In a small bowl, whisk together lime juice, olive oil, cumin, salt, and pepper. Pour over salad and toss to coat.