In a small bowl, whisk together olive oil, lime juice, cumin, chili powder, salt, and black pepper until well combined.
Drain and rinse all beans thoroughly to reduce excess sodium.
In a large mixing bowl, combine black beans, pinto beans, chickpeas, corn, red bell pepper, red onion, and cilantro.
Pour the dressing over the salad and gently toss until evenly coated.
Refrigerate for at least 30 minutes to allow flavors to blend.
Stir before serving and adjust seasoning if needed
Add diced avocado just before serving if desired.