Drain and rinse the black beans thoroughly under cold water, then pat them dry with a clean towel.
Finely chop the red onion and fresh cilantro, then dice the red bell pepper into small pieces.
In a large mixing bowl, combine the rinsed beans, chopped onion, cilantro, and diced bell pepper. Gently toss everything together to distribute the ingredients evenly.
In a small bowl, whisk together olive oil, lemon juice, a pinch of salt, and black pepper until the dressing is well combined and slightly emulsified.
Pour the dressing over the bean mixture and toss gently to coat all the ingredients evenly, making the salad shiny and vibrant.
Taste the salad and adjust seasoning with more salt, pepper, or lemon juice as desired. Let it sit in the fridge for at least 30 minutes to allow flavors to meld.
Serve the black bean salad chilled or at room temperature, garnished with extra cilantro if you like. Enjoy the fresh, colorful flavors in every bite!