Heat oil in a large, heavy skillet over medium heat. Chop onion and add to hot oil. Stir and cook 5 minutes or until tender.
Mix rice into skillet, stirring often. Rinse and drain beans and set aside.
When rice begins to get toasty, stir in chicken broth, salsa, black beans, salt and pepper. Reduce heat, cover, and simmer 20 minutes or until liquid has been absorbed and rice is tender.
Top with sliced avocado, diced tomato, and shredded cheese; serve mango on the side.