Drain and rinse the canned black beans thoroughly under cold water to remove excess salt and canning liquid. Pat them dry lightly with a clean towel or paper towel.
Finely chop half a small red onion, then soak it in cold water for about 10 minutes to mellow its sharpness. Drain well and set aside.
Finely chop about a quarter cup of fresh cilantro, pressing gently to release its fragrant oils. Set aside.
Juice the lime into a small bowl, then whisk in two tablespoons of olive oil, a pinch of salt, and freshly cracked black pepper. Stir until well combined and the dressing is slightly emulsified.
In a large mixing bowl, combine the rinsed beans, softened red onion, and chopped cilantro. Gently toss to distribute evenly.
Pour the dressing over the bean mixture. Gently fold everything together using a spoon or spatula, ensuring all ingredients are coated with the tangy dressing.
Taste the salad and adjust seasoning if needed, adding more salt or lime juice for brightness. If using, fold in halved cherry tomatoes for extra color and freshness.
Let the salad sit at room temperature for about 10 minutes to allow flavors to meld. Alternatively, refrigerate for up to 2 hours, then bring to room temperature before serving.
Give the salad one last gentle toss, then transfer to serving bowls. Garnish with extra herbs if desired and enjoy its bright, hearty flavors.
