During one of my first days working at the restaurant, the baker training me told me that we were going to make mayonnaise.

Wait, what?

I’ve never eaten much mayonnaise, as a kid because it was super gloppy (yes, that is a technical term) and later because it seemed like the epitome of processed foods that are bad for you. So I had NO IDEA that you could make mayonnaise at home with totally normal ingredients.

Blew. My. Mind.

All done

Apparently not everyone shares my amazement, though, because when I waxed poetic about the amazing process of mayonnaise to my manager, she was pretty unimpressed with the whole thing. So maybe this isn’t such a revelation to the rest of the world, but being able to start with an egg yolk (liquid, yellow) and oil (liquid, light yellow) and create a thick, pale, creamy sauce seems nothing short of miraculous.

Egg yolk

It’s also quite delicious, which is something I don’t think I’ve ever said about store-bought mayonnaise. I’ve been eating it on homemade bread and stirring it into pureed peppers and cilantro for a really yummy salsa and putting it on sandwiches and really anything else you can think of. Plus let me reiterate: four ingredients. A whisk. That is literally all you need to recreate one of the most common condiments. Still blows my mind.

The Science: Emulsions

Emulsions are like super heroes: they’re all around us even though we don’t know it. Just like you can walk right past Peter Parker without a glimmer of recognition, you probably stroll by the dairy case in the grocery store without realizing that milk and cream are both emulsions. It sounds complicated, but an emulsion is just one liquid suspended in another. It’s similar to what happens with solids dissolving (think about stirring sugar into hot coffee or tea), but in this case both parts are liquid.

The easiest emulsion to picture is salad dressing. Think about trying to mix oil and vinegar. If you pour them both into a bowl, it’s just not going to happen. The oil floats on top of the vinegar, separated as decisively as two cliques in high school. But if you throw in a little whisking action, you break up the vinegar into lots and lots of tiny pieces and you can distribute it pretty evenly in the oil. This isn’t stable at all–if you leave it alone for just a few minutes you’re back to the jocks vs. the nerds, but it gives you an idea of how emulsions work.

Making the mayo

Mayonnaise is a base of water (from egg yolk and vinegar, as well as good old water itself) with a ton of tiny spheres of oil suspended in it. It’s basically the opposite of the oil and vinegar whisked together (oil suspended in water instead of water suspended in oil), but the oil spheres are much much smaller and there are many many more of them. And they stay suspended!

How does that work? Why does mayonnaise stay creamy and all mixed up instead of separating like your salad dressing? What you need is a go-between to bring the two different sides together–someone who is on both the quiz bowl and football teams. In the case of oil and water, versatile protein molecules play the role of peacekeeper. These large molecules have some areas that want to hang out in water (hydroPHILic) and some that want to hang out in oil (hydroPHOBic). Because of their double lives, proteins help stabilize the oil spheres in their watery environment, keeping your mayo emulsified and delicious.

The Recipe: Mayonnaise

There are a lot of recipes for homemade mayonnaise on the internet, calling for all sorts of different ingredients and claiming all sorts of different foolproof methods. I kept mine simple, mostly to avoid having to go to the grocery store, and it worked out well for me, but using mustard will both make the product that much more awesome and help with the emulsifying.

I opted for a whisk because I figured that if I’m making this slightly ridiculous thing in my home kitchen, I may as well go all the way and do it without all modern technology. Plus what if there’s a terrible storm and a power outage and you just desperately need some mayo? You’ll be all set. But if you do have power, a food processor or a hand blender should be fine as well.

Yield: 1 cup mayonnaise

1 egg yolk
2 t. white vinegar
1 t. water
1/4 t. salt
3/4 c. canola oil (neutral oil like canola or safflower makes a mayonnaise that holds together well and is good for add-ins, you can also use olive oil but the emulsion isn’t as strong and it has the distinctive olive oil taste)

Whisk together the egg yolk, vinegar, water, and salt. SLOWLY add the oil. Seriously, we’re talking drop by drop at this point. Whisk continuously. Dream of mayo if your arm muscles start to cramp.

Once you’re about 1/4 cup into the oil, your mixture should be starting to look creamy and light in color, and at this point you can start pouring a LITTLE more quickly. Keep whisking! It’s ready when you’ve added all of the oil.

**Note: you’ll notice that at no point did this recipe involve a stove or an oven, so the egg is still raw. Eating raw eggs carries a risk of salmonella. Keep your mayonnaise in the fridge and eat it quickly.

Recipe adapted from the New York Times video, which also has lots of tasty ideas for how to use your mayonnaise.

Yummy on bread!


  1. Nice post! I feel like I had a really satisfying moment when I learned what it meant for an oil in water emulsion to break: I suddenly understood much better both why the various “tricks” for making it harder an emulsion more stable, as well as the tricks for fixing a broken emulsion, actually work.

    1. And this, my friends, is why science is awesome. When you actually know what’s going on, it’s a lot easier to make it work!

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