In a medium saucepan, combine quinoa and water (or broth). Bring to a boil, then reduce heat, cover, and simmer for 15 minutes. Remove from heat and let sit, covered, for 5 minutes. Fluff with a fork and let cool slightly.

In a large bowl, toss together black beans, tomatoes, corn, bell pepper, red onion, and cilantro.

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

Add the cooled quinoa and dressing to the veggie mixture. Toss gently to combine.

Gently fold in diced avocado just before serving. Taste and adjust seasoning as needed. Serve chilled or at room temperature.