In large saucepan, heat oil over medium heat; cook cauliflower, onion, garlic, mushrooms and pepper, stirring occasionally, for 4 minutes or until onion is softened.
Add ketchup, black and green olives, green pepper, tuna, shrimp and vinegar; bring to boil. Reduce heat and simmer, stirring occasionally, for 20 minutes or until thickened enough to mound on spoon. Stir in parsley. (Make-ahead: Cover and refrigerate for up to 2 days or freeze for up to 1 month. Makes 4 cups.