Separate cauliflower-ettes and slice them thin. Slice the onion into rings and separate rings. Add them to the cauliflower together with the sliced olives. Marinate it all in the dressing with black pepper to taste, anywhere from 1/2 an hour to overnight.
When ready to serve, cut or tear the lettuce into small pieces. Put them in a bowl or on a platter, pour the marinated mix over it and crumble the bleu cheese on top.