In a large, resealable plastic bag combine the marinade ingredients. Place the steak pieces in the bag, press the air out of the bag, and seal tightly. Turn the bag to distribute the marinade, place in a bowl, and refrigerate for 4 to 24 hours.
Separate the leaves from the head of lettuce, wash and dry them, and refrigerate until ready to serve.
Remove the steaks from the bag and reserve the marinade. Pour the marinade into a small saucepan, bring to a boil, and boil for 3 to 4 minutes. Set aside. Allow the steaks to stand at room temperature for 15 to 30 minutes before grilling.
Cook the rice according to package instructions. Drain, and rinse briefly to cool.
Prepare the grill for direct cooking over high heat (450° to 550°F).
Pat the steaks dry, and then grill over direct high heat, with the lid closed, until cooked to your desired doneness, 4 to 6 minutes for medium rare, turning once. Remove from the grill and let rest for 3 to 5 minutes. Cut the meat across the grain into thin slices, and place in a bowl with any accumulated juices.
In a bowl combine the scallions, jalapeños, and cilantro. Place one or two spoonfuls of rice into the center of two stacked lettuce leaves. Top with steak and the vegetable garnish. Drizzle with the reduced marinade. Serve with lime wedges.