Stopped off at 5-Guys tonight. Ordered a cheeseburger with lettuce, onions and pickles with sides of ketchup, relish and mayo.
That sure looks like the special sauce. There's something ephemerally wrong, but it's 97% correct.
I declare success. It is not the same as a Big Mac. It is better in every conceivable way! It's like if a Big Mac was made from food.