Inside a stack of three sesame buns, you'll find two patties, cheese, lettuce, pickles, onions, and a mouthwatering "special ... added: "McDonald's should bottle and sell Big Mac Sauce." ...
So what exactly is inside that "special" relish ... Another added: "McDonald's should bottle and sell Big Mac Sauce." A third queried: "Where the hell do I get Dusseldorf mustard?