Remove 4 to 6 big cabbage/lettuce leaves (if using) from the head of cabbage/lettuce. I had trouble with this, I think it will be easier if you cut off the base first (head smack!). Place each leaf on its own small plate.
In a medium bowl, combine the raw corn kernels, onion, bell pepper, cherry tomatoes, cilantro, chili powder, cayenne pepper (if using) and the juice of two limes. Season with salt and pepper to taste and toss in a teaspoon of olive oil. Set aside for thirty minutes, if you can swing it.