There is a certain type of restaurant out there that gets away with way too many crimes against the language of food. The kind that desperately wants to be hip, but just kind of fails. I guarantee that all of them have at least one menu item that comes with a gussied up aioli of some sort: lemon pepper aioli, harissa aioli, and so on. If you ask any of the servers there “what is aioli?”, they’ll probably tell you that aioli is the same thing as mayonnaise. Because there probably is some hack in the kitchen dumping the contents of a jumbo-sized spice container into a jumbo-sized tub of Hellman’s.
The fact of the matter is that mayo + seasoning does not make an aioli, nor are mayo and aioli one and the same. And while we’re on the subject, that Hollandaise on the benedicts could technically be described as a “hot mayo,” but that would only be telling half the story. Also, it’s most definitely not made with cream, as I was once told during brunch at a self-described “indie eatery.”
Mayonnaise, aioli, and Hollandaise are linked by the fact that they’re all emulsions. At the molecular level, this means that they contain tiny droplets of fat suspended in water. They also all share egg yolks as a common emulsifying ingredient. Yolks are actually a made-in-nature emulsion all by themselves. They’re chock full of lipoproteins, which are fats coated in a protein-based layer that simply loves to attach itself to water.
To make any of these sauces, you start out by combining the yolks with a pinch of something acidic (usually vinegar or lemon juice, which not only adds flavor, but also helps keep the proteins from getting too tangled). Then, you gradually whisk or blend in the oil or fat. Along the way, the fat particles get tinier and tinier (and start to suspend themselves), while the proteins do their best to make the water and fat co-exist peacefully, despite the fact that they usually don’t get along all that well.
So to sum it up, mayonnaise, aioli, and Hollandaise are all egg-based emulsions created using the same basic technique. Then what’s the difference? Let’s break it down:
As cooking encyclopedia Larousse Gastronomique puts it, mayonnaise is “a cold emulsified sauce consisting of egg yolks and oil blended together.” Prior to the popularization of refined cooking oils in the 20th century, that “oil” would have almost certainly been olive oil (and the recipe that accompanies the Larousse entry calls for such). Nowadays, however, it’s accepted that mayo can include just about any sort of oil, especially neutral ones like canola or soybean.
While we generally think of mayonnaise as that gloopy, light beige-ish vinegar and mustard-accented sauce, pretty much any yolk + oil emulsion could qualify as a mayo according to the basic definition. In other words, aioli and hollandaise are specific types of mayo (but not all mayos are aioli or hollandaise). Get our Homemade Mayonnaise recipe.
If there’s one good reason why you shouldn’t label just any mayonnaise as an aioli, it’s because aioli goes way, way back, so it deserves some respect. It can be traced back to at least the first century A.D., when Pliny described alioli, a mixture of garlic (a weak emulsifier) pounded with olive oil that was common in present-day Spain. Eventually, the recipe picked up some egg yolk and became more strongly associated with Provençe and the dishes from that region that utilize the sauce.
Some hardcore chefs will tell you that true aioli can only be made with a mortar and pestle, although really no one will bat an eyelash if you opt for the food processor or blender. Aioli absolutely must contain olive oil and must contain garlic, however. So while aioli is a garlicky riff on olive oil mayonnaise, adding any ol’ cockamamy flavor to your mayo does not make an aioli. Which is why I would like to beg restaurants to stop passing off every single mayo-ish sauce as an aioli. I can see right through your shenanigans. Get our Basic Aioli recipe.
As one of the five French mother sauces, hollandaise commands a certain amount of prestige. Using butter as its main fat, it has a reputation as being especially tricky because it needs to be made at a just-warm-enough temperature for the butter to stay liquid and melty, while not being so hot that it completely cooks the yolks (scrambled eggs floating in butter, anyone?).
Once you’ve got the temperature under control, however, hollandaise is really not that difficult to put together—the gentle heat actually helps facilitate emulsification and thickening. The sauce also contains a smaller ratio of fat to egg than mayonnaise. According to Harold McGee’s On Food and Cooking, the fat content of hollandaise is “between one and two thirds of the total volume,” whereas in mayo it’s “as much as 80 percent.” So you can use that as an excuse to drench your Sunday brunch in all of hollandaise’s buttery goodness. Get our Easy Blender Hollandaise recipe.
Miki Kawasaki is a New York City–based food writer and graduate of Boston University's program in Gastronomy. Few things excite her more than a well-crafted sandwich or expertly spiced curry. If you ever run into her at a dinner party, make sure to hit her up for a few pieces of oddball culinary trivia.