The Filet-O-Fish Ordering Trick That Costs $0 But Gets You A Lot More Flavor

McDonald's has been serving the Filet-O-Fish sandwich in nearly the same way since it was invented in 1962. The breaded Alaskan pollock filet comes dressed with a half slice of American cheese and tartar sauce, and the unique steamed bun adds a nice textural contrast. That's all there is to it. As with any menu item, McDonald's allows you to customize a Filet-O-Fish however you like. For a fee, you could add more cheese or bacon — but there are also free upgrades that add a new flavor dimension to your Filet-O-Fish.

Fish is a versatile ingredient, and the breaded Alaskan pollock acts as a blank canvas for many flavors. A simple upgrade with pickles and mustard can bring more brightness and sharpness to a Filet-O-Fish. You may not think of mustard at first, but it pairs well with seafood. The condiment cuts through the fattiness of fish, and the soft, sweet flavor of pollock is complemented by its acidity. Pickles and fish are also a classic flavor duo for much the same reason, especially in a Jamaican dish like escovitch. A Filet-O-Fish with pickles may be a world away from the rest of the flavors, but you're in the ballpark.

Onions add a mild, sweet, and savory note, especially since McDonald's uses rehydrated onions that have lost a lot of their sharpness. It also offers fresh, slivered onions on burgers like the Quarter Pounder, so you can choose those as well for an added bite.

McDonald's has a handful of toppings that are generally free upgrades for any sandwich. That includes onions, pickles, ketchup, and mustard. Burgers from McDonald's often come with lettuce, tomatoes, and mayo, but those are no longer free at every location. Some Redditors have even reported that pickles come with an extra cost now, too. Usually, this is between 30¢and 50¢, but it is up to the individual franchise. If you want to try this British pub-style upgrade using fries, that will definitely come at a cost.

Like mayo, extra tartar sauce will likely cost extra. Swapping mustard for the spicy mustard used with McNuggets may also come with a charge. Some locations may offer these upgrades for free, so the best way to find out is to ask. When Tasting Table covered the delicious ways to customize a Filet-O-Fish, one suggestion was to swap the tartar sauce for Big Mac sauce. That one might cost you up to $0.50, though. Extra sauces, even ketchup and mustard, may come with a fee when you order through the app, so keep that in mind. 

Since it's often hard to customize orders on the app, you could end up being charged for extras that the store might give to you for free if you go in person. Another advantage of ordering in person is the ability to make more unusual requests. For instance, McDonald's has lemon wedges for iced tea. You could request the lemon to go with your fish, and squeeze a little juice for a burst of citrus. With some creativity and little to no money, you can easily customize a next-level fish sandwich.