In a large bowl combine the black beans with a sprinkle of cumin and garlic powder, top with corn, then romaine leaves.
In a small bowl, combine the tomatoes, black olives and scallions. Put this mixture on top of the lettuce.
Just before serving, combine the avocado, cilantro and lime juice in a small bowl. Put this mixture on top of the tomato and olive mixture. Serve with the Creamy Cilantro Lime Dressing.