Mix all ingredients except mayonaisse. Refrigerate until serving. Mix in mayonaisse just before serving.
To roast peppers:
Preheat oven to 425 degrees. Quarter peppers and remove stems, membranes, and seeds. Place cut side down on a foil-lined baking sheet. Bake 20-30 minutes, until skin is bubbly and browned. Place in new brown paper bag, seal & let stand 20 minutes. Pull skin off slowly, using paring knife. Slice.