1. Place bell peppers and onion on grid over medium, ash-covered coals. Grill vegetables 10 to 12 minutes (over medium heat on preheated gas grill 10 to 12 minutes) until tender, turning occasionally.
2. Chop bell peppers and onion; place in a medium bowl. Add beans, cilantro, lime juice, oil, garlic, salt and black pepper; mix well. Serve immediately or cover and refrigerate until ready to serve.