Rinse the quinoa under cold water to remove any bitterness. Cook the quinoa according to package instructions, then let it cool slightly.

In a large bowl, combine the black beans, corn, red bell pepper, and red onion. Mix well.

In a small bowl, whisk together the lime juice, olive oil, cumin, chili powder, salt, and pepper to make the dressing.

Add the cooked quinoa to the large bowl with the vegetables. Pour the dressing over the mixture and toss gently to combine.

Gently fold in the avocado slices and chopped cilantro, being careful not to mash the avocado.

Divide the quinoa mixture into serving bowls. Garnish with extra cilantro and a lime wedge if desired.