In a medium saucepan, combine the rinsed quinoa and water. Bring to a boil, then reduce heat to low, cover, and simmer for about 15 minutes or until the quinoa is fluffy and water is absorbed. Remove from heat and let it cool slightly.
In a large bowl, combine the black beans, corn, red bell pepper, cherry tomatoes, red onion, and cilantro.
In a small bowl, whisk together the lime juice, olive oil, cumin, chili powder, salt, and pepper.
Add the cooked quinoa to the large bowl with the vegetables and mix well. Pour the dressing over the salad and toss to combine.
Gently fold in the diced avocado just before serving to prevent it from mashing.
Chill the salad in the refrigerator for at least 30 minutes to allow the flavors to meld. Serve cold or at room temperature.