Let me start by saying this isn't a post about cutting calories or cholesterol; it's about making the most of whatever ingredients you have on hand. For bakers like me, leftover egg whites are a way of life. From the yolky egg wash on a cherry pie to the yolk-enriched dough of vanilla bean alfajores, my favorite recipes orphan egg whites at every turn.
It can take ages for such desserts to generate enough leftover whites for a big project like Angel Food Cake, so for the most part I'll just slip my extra whites into batches of cheesy scrambled eggs or use them to bulk up the more forgiving custards used in a quiche or frittata.
While that's all well and good, the idea of mayonnaise promises a far more versatile alternative. I first heard about "white" mayonnaise standing in line for poke at Chikarashi in New York, where the manager described it as a delicate dressing for their hamachi bowl. I thought the idea was very smart—why muddy the unique flavor of amberjack with the custardy taste of yolks?
Beyond that, I saw it as a clever use of something that's all too often thrown away: that lone egg white lurking in a ramekin in the back of my fridge. But when I asked Kenji and Daniel about the technique, their collective response was a Scooby-like huh? Which is how we found ourselves live-tweeting an impromptu eggsperiment at 11 o'clock on a Friday night.
While Kenji was (and perhaps still is) fairly skeptical of the concept, Daniel and I went in with high hopes. We both knew from experience that egg whites and fat don't have to be enemies, he from an extensive takedown of the age-old myth that even a trace of fat will ruin a meringue, and me from a lifetime of whipping up of Swiss meringue buttercream, a literal pile of egg whites and fat. We were sure something would happen, but would it be mayonnaise?
In short, yes. Using the same technique and ratio of ingredients as Kenji's 2-Minute Mayo, we found egg whites whip into a mayonnaise as silky, soft, and spreadable as any other.
The key is to remember that a lone egg white offers less in weight and volume than a whole egg, so it requires less oil—in other words, you can't think of eggs and whites as a one-to-one swap. If the oil isn't adjusted proportionally, the egg white will churn up in big, fluffy curds like an over-whipped meringue.
You can doctor it with lemon juice and mustard to keep the flavor profile relatively traditional, but neither ingredient is essential to the mayo's success if you'd prefer to season things differently. What is important is to reach for a neutral oil, since an immersion blender can oxidate olive oil, resulting in an unpalatable bitterness. My go-to alternative is safflower oil (I'm the type of weirdo who finds canola oil inherently fishy and rank), but feel free to use whatever you keep on hand.
As per Kenji's method, all the ingredients are combined in a narrow container. If your immersion blender comes with a custom "blending cup," all the better! But if not, I've had great success with cocktail shakers and wide-mouth jars, too. The trick is to keep it as narrow as possible so the oil can be pulled down by the blades bit by bit.
The technique itself couldn't be any simpler—just zip-zip and you're done. If need be, raise the immersion blender to help incorporate any remaining oil, but thanks to the recipe's low volume, egg white mayonnaise comes together fast. We're talking about 20 seconds, tops.
It's a quick route to a mini batch of thick and creamy mayonnaise, though you could certainly double it if you prefer. But in my two-person household, a single egg white yields exactly enough mayo to slather on a couple of sandwiches or a few ears of grilled corn. Sure, its flavor is completely neutral, but I see it as an elegant simplicity that puts more interesting ingredients center stage.
Besides, the nuance of egg yolks and olive oil is lost in so many mayo-centric dishes (think spinach and artichoke dip), making "white mayo" a great option when you're whipping it up as an ingredient for something else.
Ultimately, "white mayo" is a tool that can help you take advantage of ingredients you already have on hand. If that's a fridge full of whole eggs, then go make Kenji's two-minute mayo! If you'd prefer the yolky richness of a traditional mayonnaise, have at it! But for bakers all-too-often saddled with leftover egg whites, or cooks wanting to improve the texture and richness of a dish without altering its flavor, this unusual mayonnaise is a neat trick to have up your sleeve.