In a medium saucepan, bring 2 cups of water or vegetable broth to a boil. Add the rinsed quinoa, reduce heat to low, cover, and simmer for 12-15 minutes until the quinoa is tender and the liquid is absorbed. Fluff with a fork and let it cool slightly.
While the quinoa cooks, prepare the vegetables: Halve the cherry tomatoes, dice the red bell pepper, finely chop the red onion, and chop the cilantro. If using frozen corn, thaw it; if using fresh, lightly steam or blanch it.
In a large mixing bowl, combine the cooked quinoa, black beans, cherry tomatoes, red bell pepper, corn, red onion, and cilantro. Toss gently to mix.
In a small bowl or jar, whisk together the dressing ingredients: olive oil, lime juice, ground cumin, chili powder, salt, and black pepper. Adjust seasoning to taste.
Pour the dressing over the quinoa mixture and toss until everything is evenly coated. Let the salad sit for 5-10 minutes to allow the flavors to meld (optional but recommended).
Serve the quinoa and black bean salad in bowls or as a side dish. Top with diced avocado if desired. Enjoy it chilled or at room temperature for a refreshing, nutrient-packed meal!