Rinse the quinoa under cold water. Place it in a saucepan with 2 cups of water and a pinch of salt. Bring to a boil, then reduce heat, cover, and simmer for 15 minutes until the water is absorbed. Fluff with a fork and let it cool to room temperature.
In a large mixing bowl, combine the cooled quinoa, black beans, corn, diced red bell pepper, and diced yellow bell pepper.
In a small bowl, whisk together the olive oil, lime juice, cumin, salt, and black pepper until smooth. Stir in most of the chopped cilantro.
Pour the dressing over the quinoa mixture and toss gently until everything is evenly coated. Sprinkle the remaining cilantro on top before serving.