In a small bowl whisk together olive oil, red wine vinegar, lime juice and minced garlic. Season with salt and pepper to taste.
In another bowl combine black beans, mango, tomatoes, orange pepper, cilantro, and onion. Drizzle with olive oil mixture and toss salad until everything is evenly coated. Serve immediately or cover and chill until ready to serve.
To serve: Cut avocados in half. Remove pit. Place avocado halves (2 halves per serving) cut side up onto four plates. Scoop one forth of the black bean mango salad per serving onto avocado halves, allowing remainder to be served on the side.