Fry sauce is a regional condiment served with French fries. It is usually a simple combination of one part ketchup and two parts mayonnaise. When spices and other flavorings are added, it is similar to—but thicker and smoother than—traditional Russian dressing and Thousand Island dressing. In the United States, fry sauce is commonly found in restaurants in Utah and Idaho, as well as available by mail-order. Occasionally other ingredients such as barbecue sauce are substituted for ketchup, and other variations (created independently of the Utah version) exist outside of the United States.
In the United States 
The Utah-based Arctic Circle restaurant chain claims to have invented fry sauce around 1948. However, a recipe for Thousand Island dressing dating from 1900 has mayonnaise, ketchup, and pickles as the only ingredients, albeit in a 1:1 ratio. Arctic Circle serves fry sauce in its restaurants in the western United States. Many other fast-food restaurants and family restaurants in the region, such as Carl's Jr, Crown Burgers, Apollo Burger, Astro Burger and Hires Big H, also offer their own versions of the sauce. Some variations include chopped pickles, chopped onions, and shredded cabbage. Utah franchise locations of McDonald's also carried fry sauce until 1997. Many other national fast food restaurants in Utah and nearby states serve fry sauce.
In Idaho and the Pacific Northwest, fry sauce is also popular and is found at many local restaurants as well as chains such as Dairy Queen and Sonic.
In the 2008 film Step Brothers, there is a scene in which the main characters referred to a home-made sauce of ketchup and mayonnaise as "fancy sauce".
In early 2010, Stephen's Gourmet began distributing a bottled, shelf-stable traditional fry sauce to grocery store and mass merchandise chains throughout the United States. It hit the shelves in Utah and the Pacific Northwest in May 2010. Prior to that, a company bottled fry sauce sold mainly in Utah called "Some Dude's Fry Sauce." Similar to Stephen's variety, it is also shelf stable and sold in grocery chains throughout Utah and parts of Idaho. The Utah-based Arctic Circle also now sells their fry sauce in bottles at most of their locations.
Outside the USA 
In Argentina, a similar condiment known as salsa golf, or "golf sauce," is a popular dressing for fries, burgers, and steak sandwiches. According to tradition, the sauce was invented by Nobel laureate and restaurant patron Luis Federico Leloir at a Golf Club in Mar del Plata, Argentina, during the mid-1920s.
In Brazil, many fast food restaurants provide "rosé sauce" (equal parts mayonnaise and ketchup, sometimes with hot sauce added) alongside the traditional ketchup and mustard with fries and onion rings.
In Colombia, a sauce similar to fry sauce called "salsa rosada" (pink sauce) is widely used. This sauce is packed commercially by many local distributors. It is most commonly used on hot dogs, burgers, fries and chips (there is often a pack of "salsa rosada" taped onto chip bags)
In Costa Rica, a salad dressing called Salsa Rosada (pink sauce) is served with a cabbage salad. The main Salsa Rosada ingredients are ketchup and mayonnaise.
In Spain, a sauce named "salsa rosa" (pink sauce) is usually served along with shellfish or occasionally as a substitute for ketchup. Its ingredients are ketchup and mayonnaise but proportions may vary.
In Belgium, the mixture of mayonnaise and ketchup is known as cocktailsaus or sauce cocktail, often refined with the addition of some paprika powder or whisky. Mayonnaise and ketchup separately on a dish (usually fries) and topped with freshly chopped onion is known as speciaal. A mixture of ketchup, mayonnaise, finely chopped onion and sometimes spices is known as "riche", literally "rich sauce".
In France, many Turkish restaurants and other fast-food establishments serve fry sauce and call it sauce américaine; it is also common for customers to request "ketchup-mayo"—a dab of mayonnaise and a dab of ketchup—alongside their French fries at such places. Both American sauce and the more thousand-island like sauce cocktail (somewhat similar to that of Iceland) can often be found in supermarkets, and occasionally also premixed "ketchup-mayo."
In Germany, a popular product called 'Rot Weiss', meaning 'red white' is sold in toothpaste-style tubes, and consists of ketchup and mayonnaise, while "Pommes-Soße" ("Pommes" is the commonly used word for "Fries," so this is "Fry Sauce") is a lightly spiced mayonnaise.
In Iceland, a condiment similar to fry sauce called Kokteilsósa ("cocktail sauce") is popular. Originally, the sauce was used with prawn cocktails—hence the name—but in course of time, it became indispensable with French fried potatoes. However, Icelanders use the sauce with many other dishes, including hamburgers, pizza, hotdogs, and fried fish. Substituting sour cream for some part of the mayonnaise is also popular, making the resulting sauce thicker.
In Puerto Rico, the sauce is commonly known "mayoketchup" and is prepared with ketchup, mayonnaise, garlic and a hint of lemon. The sauce is often used as a dip for sorullos, tostones, and other fried dishes as part of the traditional cuisine of Puerto Rico.
See also 
- French fries - accompaniments
- Marie Rose sauce
- Comeback sauce
- Thousand Island dressing
- Russian dressing
- Vergakis, Brock (January 6, 2007). "My oh my do we love fry sauce!". The Deseret News . pp. .
- A Book of Famous Old New Orleans Recipes, New Orleans, 1900 full text, s.v. Breaded Veal Rounds and Thousand Island Dressing
- a review of Selah, Washington's King's Row drive in published by the Yakima Herald-Republic titled On the Menu—King's Row Drive-In refers to its "fabulous fry sauce"
- SalsaGolf at the Spanish Wikipedia
- "Sauces classiques" from Bénédicta
- "Sauce ketchup mayo" in Bénédicta's "Oh Ouizz!" line
- Kokteilsósa in Iceland