Put the black beans in a strainer and rinse thoroughly; set aside to drain.
Peel the mango, slice pieces off the pit, and dice into approx. 1/2-inch cubes. Set aside.
Combine cooked rice, green onions, cilantro, salsa, lime juice, olive oil, salt, and pepper in a large mixing bowl. (Note: add salt only if the beans are salt-free.)
Add the diced mango and then the drained beans, stirring only enough to mix.
Hint 1: The purpose of the rice is to absorb extra liquid and keep a nice texture, - so use rice which is well-separated and a bit on the dry side.
Hint 2.: You can't have too much cilantro :-)