Cook the rice according to the package directions.
Remove the rice from the heat. (If you want to serve this salad immediately rather than allowing it to chill for a while, put the rice in the freezer for 5 minutes to cool it.)
Meanwhile, in a large bowl, combine the beans, mango, onions, scallions, lime juice and cilantro (optional).
Add the rice, season it with the salt, and toss gently. Chill it for at least 10 minutes (an hour or more is ideal) and up to 24 hours.
Serve the salad on its own or wrapped in large lettuce leaves, warm tortillas, or both.