Place the quinoa along with 2 cups salted water in a medium saucepan. Cover and bring to a boil, then reduce to the lowest heat setting. Simmer until water is completely absorbed and quinoa is fluffy, about 20 minutes.
While the quinoa is cooking, make the Creamy Avocado Dressing. Combine all of the dressing ingredients in a blender or food processor and blend until smooth.
In a large bowl, combine quinoa, black beans, tomatoes, bell peppers, avocado, cucumber, corn, red onion. Pour dressing over quinoa salad and stir until salad is well coated. Season with salt and pepper. Squeeze fresh lime juice over the salad, so the avocado doesn't brown. Garnish with chopped cilantro and serve at room temperature or chilled.