the olive oil, vinegar, and cilantro
together in a large bowl until blended. Season lightly with salt and pepper. Add the beans, mango, jicama, and onion
and toss gently to coat with the dressing
. Season with salt and pepper, to taste. Serve right away or let stand at room temperature for up to 30 minutes. Toss and check the seasoning before serving.
Note: If you can't find jicama, which adds an apple-y note to the salad, substitute a large green apple. Core the apple, leave the skin on, and dice it as you would the jicama.