Step 1: Begin by preparing your black beans. Drain them completely from their can and rinse them thoroughly under cold running water in a colander until all the cloudy liquid is gone. Let them drain for a few minutes.
Step 2: Dice the avocados. Cut each avocado in half lengthwise, remove the pit, and score the flesh in a crosshatch pattern without piercing the skin. Scoop out the diced avocado with a spoon into a large mixing bowl. Aim for roughly 1/2 to 3/4-inch pieces.
Step 3: Prepare the other vegetables. Finely mince the red onion; a fine mince ensures its flavor is distributed without being overpowering. Chop the bell pepper into small, even pieces, similar in size to the avocado dice. Roughly chop the fresh cilantro.
Step 4: Combine all the main ingredients in the large mixing bowl. Add the rinsed black beans, diced avocado, minced red onion, chopped bell pepper, and fresh cilantro.
Step 5: Dress the salad. In a small separate bowl, whisk together the fresh lime juice, extra virgin olive oil, ground cumin (if using), and a pinch of salt and black pepper.
Step 6: Season and gently toss. Pour the dressing over the ingredients in the large bowl. Using a large spoon or spatula, gently fold the ingredients together. Be careful not to overmix, as this can mash the delicate avocado. The goal is to coat everything evenly while keeping the avocado pieces intact. Taste and adjust seasonings as needed, adding more salt, pepper, or lime juice to your preference. Serve immediately or chill for 30 minutes for flavors to meld.