1Heat coals or gas grill for direct heat. Cut three 18x12-inch pieces heavy-duty foil. Spray with cooking spray.
2Mix beans, rice, onions, 1/4 cup cilantro, the oil, lime juice, garlic and salt. Place 2 bell pepper halves on one side of each foil piece. Fill with bean mixture.
3Fold foil over peppers so edges meet. Seal edges, making tight 1/2-inch fold; fold again. Allow space on sides for circulation and expansion.
4Cover and grill packets over medium heat 15 to 20 minutes or until peppers are tender. Place packets on serving platter. Cut large X across top of each packet; fold back foil. Sprinkle with tomato and additional cilantro.