1 1/2poundsbeef tenderlointrimmed and cut into 30 cubes
1red bell peppercut into 18 pieces
2black-ripe plantainspeeled, and each cut into 9 pieces
Non-aerosol cooking spray
Diagonally-cut green onionsoptional
Preheat outdoor or indoor grill. In a food processor or blender container, combine first 9 ingredients (green onions through peppers); process until smooth. Place green onion mixture, beef and bell pepper pieces in a large zipper-topped plastic bag; seal and turn to coat. Marinate in refrigerator for 20 minutes. Transfer beef and bell pepper pieces from plastic bag (discarding marinade) to a large bowl. Add plantain pieces and toss well to coat. Onto each skewer, alternately thread 5 beef cubes, 3 red pepper pieces and 3 plantain pieces. Lightly coat kebabs with cooking spray and place them on grill rack coated with cooking spray. Cook for 4 minutes per side for medium-rare, or until they reach desired level of doneness. Garnish with green onion pieces and serve with lime wedges, if desired.
DO-AHEAD TIP: If using bamboo skewers, soak them in water for 30 minutes prior to grilling. Marinate beef and bell pepper pieces for 20 minutes.