Use a can opener to open the black beans, then rinse them thoroughly in cold water and drain well. Place them in a large mixing bowl.
Dice the red bell pepper and chop the red onion into fine pieces, then add them to the bowl with the beans. Chop a handful of cilantro and sprinkle it over the mixture.
In a small jar or bowl, combine the olive oil, freshly squeezed lime juice, ground cumin, and a pinch of salt and pepper. Shake or whisk until well blended and fragrant.
Pour the dressing over the bean and vegetable mixture. Gently toss everything together until the ingredients are evenly coated and vibrant in color.
Taste the salad and adjust seasoning by adding more lime juice, salt, or pepper if desired. Let it sit for at least 15 minutes to allow flavors to meld and the vegetables to soften slightly.
Give the salad a gentle toss again, then serve it chilled or at room temperature, garnished with extra cilantro or lime wedges if you like. Enjoy this fresh, hearty dish!