1. Cook quinoa: In a saucepan, bring quinoa and water to a boil. Reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let sit for 5 minutes, then fluff with a fork.
2. Prepare vegetables: While quinoa is cooking, prepare the black beans, corn, cherry tomatoes, avocado, and cilantro.
3. Mix salad: In a large mixing bowl, combine cooked quinoa, black beans, corn, cherry tomatoes, avocado, and cilantro.
4. Make dressing: In a small bowl, whisk together lime juice, olive oil, cumin, salt, and black pepper.
5. Combine: Pour dressing over the salad and toss to combine. Serve immediately or chill in the refrigerator for later.