Rinse the quinoa in a fine mesh strainer. Add it to a pot with the water and bring to a boil. Reduce the heat to low, cover, and simmer for 15 minutes until the water is absorbed. Remove from heat, fluff with a fork, and let cool to room temperature.
Place the cooled quinoa in a large mixing bowl. Add the black beans, diced mangoes, chopped jalapeños, red onion, and cilantro.
In a small bowl, whisk the lime juice, olive oil, salt, and black pepper until combined.
Pour the dressing over the quinoa mixture and toss gently until everything is evenly coated.