The Filet-o-Fish is a McDonald’s classic that debuted way back in 1965 and has remained a menu mainstay. There are many hacks that reimagine the OG fried fish sandwich, like giving it a drool-worthy saucy swap, transforming it into a surf and turf treat, or turning it into a British classic with one addition. Another that’s gotten online attention gives the Filet-o-Fish a spicy tang by topping it with a McDonald’s condiment that can be hard to find: hot mustard sauce.
The sandwich only has four ingredients — fried Alaskan pollock filet, American cheese, tartar sauce, and bun — so swapping or adding one makes a real difference. One YouTuber who gave this hack a big thumbs-up replaced tartar sauce with the hot mustard sauce, which he described as a combination of brown and honey mustards with spice. The deep yellow mustard sauce does have sweetness with its mustard flavor and is mayonnaise-based, made with egg yolks and oil. However, despite its “hot” name, it doesn’t have much heat; the YouTuber pegged it at just 1½ to 2 out of 10. You can also try this hack without holding the tartar sauce, allowing the zesty flavors of the two condiments to blend.
While a fish and mustard combination might seem unusual, it’s really not. In fact, this Filet-o-Fish zhush can be seen as a rejiggering of recipes that coat fish with mustard before breading it to fry. The mustard sauce is on top of the breaded crust here instead of under it but adds zippy flavor to the mild fish both ways.
McDonald’s hot mustard sauce may be tough to track down
Trying this out for yourself may not be as easy as heading to your nearest McDonald’s because finding the hot mustard sauce can be hit or miss. Although it was one of the four original dipping sauces for Chicken McNuggets when they were introduced in 1983 (along with honey, sweet and sour, and barbecue), it was discontinued in the U.S. in 2015. But many American McDonald’s franchises continue to have the hot mustard sauce available years later, with customer reports of it from states including Wisconsin, California, Virginia, North Carolina, and Michigan.
If you don’t have luck finding the sauce, a former McDonald’s corporate chef has said that after researching and doing taste tests, he believes the closest dupe you can buy is Pilsudski Sweet Hot Mustard with Honey (via TikTok). There are also plenty of internet copycat recipes that try to nail the taste, using ingredients like prepared and dry mustard, corn syrup, soy sauce, mayonnaise, and hot sauce.
Superfans who won’t settle for anything less than the original have the option of buying it from entrepreneurial online sellers. An internet search can find the hot mustard sauce being sold in bundles of the small rectangular plastic cups — all, of course, for a substantial markup.
