McDonald's® Big Mac Sauce® ("Special Sauce") If you like Big Macs, it's probably because of that tasty "secret" spread that is plopped onto both decks of the world's most popular double-decker hamburger. So what's so special about this sauce? After all, it's basically just thousand island dressing, right? Pretty much. But this sauce has a bit more sweet pickle relish in it than a typical thousand island salad slather. Also, I found that this clone comes close to the original with the inclusion of French dressing. It's an important ingredient - ketchup just won't do it. That, along with a sweet & sour flavor that comes from vinegar and sugar, makes this sauce go well on any of your home burger creations, whether they're Big Mac clones or not. This is the closest "special sauce" clone you'll find anywhere. 1/2 cup mayonnaise 2 tablespoons French dressing 4 teaspoons sweet pickle relish 1 tablespoon finely minced white onion 1 teaspoon white vinegar 1 teaspoon sugar 1/8 teaspoon salt 1. Combine all of the ingredients in a small bowl. Stir well. 2. Place sauce in a covered container and refrigerate for several hours, or overnight, so that the flavors blend. Stir the sauce a couple of times as it chills. Makes about 3/4 cup.