How Thousand Island Dressing Became The Base For Fast Food Secret Sauce

The origin of the Reuben sandwich may be hotly contested between that of New York's Arnold Reuben and Nebraska's Reuben Kolakofsky, but what isn't disputed is how delicious the combination of rye bread, corned beef, Swiss cheese, sauerkraut, and Thousand Island is. While some prefer a spicier version, with Russian dressing, there's no denying that the sauce is the key to the sandwich's popularity.

Inspired by the popularity of the Reuben, the sweet and zesty dressing had become a key staple of the deli sandwich by the 1950s, and soon fast food restaurants were using it on their own sandwiches and burgers. In 1961, In-N-Out Burger used a version of Thousand Island for its 'animal style' burgers. Big Boy's double-decker burger's secret sauce was another rendition of the dressing, and Jack in the Box's Bonus Jack burger released in 1970 also featured its own Thousand Island-based secret sauce. The dressing went on to become a staple for many other fast-food chains' burger sauces, such as Steak n' Shake and Shake Shack.

For many years many also assumed McDonald's Big Mac sauce was a Thousand Island knockoff, but when it was discovered that ketchup — a Thousand Island staple — wasn't one of the ingredients, that notion was put to rest. What it does have in common with Thousand Island dressing, however, is that it's basically a mix of condiments any fast food restaurant would have on hand. And since these condiments all belong on a sandwich, why not this dressing?

The dressing is simple and easy to customize

It's easy to see why Thousand Island dressing is such a popular fast food sauce: The ingredients are all common fast food joint staples. But mixed together it tastes almost decadent, rich and tangy from the mayonnaise, sweet from the relish, and with a bite from the ketchup. After the basics, the recipe is customizable with spices, vinegar, or whatever the fast food restaurant wants to add to distinguish its sauce from the other guys'.

Big Boy Founder Bob Wian told the Santa Ana County Register that chili sauce was an ingredient in its Big Boy sauce, and talked about how hard it is to keep a secret sauce secret, "There's more plagiarism in this business than in any other. It's not a case of stealing, it's adopting." And that's just what all the fast food chains, did. It's thought that In-N-Out's secret sauce adds vinegar and sugar to make its secret sauce stand out. In "Shake Shack: Recipes & Stories" a cookbook put out by the chain, it's stated that Shake Shack's sauce adds Dijon mustard and cayenne pepper, and uses pickle brine instead of pickle relish. Steak 'n Shake's Frisco sauce is thought to be a Thousand Island base with the addition of garlic powder and French dressing. While every restaurant alters its secret sauce a bit to make it unique, if it contains some version of mayo, ketchup, and relish, it's safe to say it's a variation of Thousand Island dressing.