Use a can opener to open the cans of black beans, then rinse them thoroughly under cold water until the water runs clear. Drain well and transfer to a large mixing bowl.
Finely chop the red onion and add it to the bowl with the beans, along with the freshly chopped cilantro and parsley. Toss gently to combine.
In a small jar or bowl, squeeze the juice of the limes, then add the olive oil, cumin, salt, and black pepper. Shake or whisk until the dressing is well combined and slightly emulsified.
Pour the lime dressing over the bean mixture in the large bowl, then gently toss to coat all the ingredients evenly. The beans should glisten lightly and smell citrusy.
Taste the salad and adjust the seasoning by adding more salt, pepper, or lime juice if desired. Let the salad sit at room temperature for about 10-15 minutes, or refrigerate for up to 2 hours to allow flavors to meld.
Give the salad a final gentle toss, then serve in bowls, garnished with extra herbs if you like. Enjoy this bright, crunchy, and tangy black bean salad!