When I last worked on making vegan mayonnaise, I tried a whole slew of egg replacements before I finally settled on soft tofu. It works, but it requires a good amount of tofu—enough that you can taste the tofu a bit in the finished product. It's also not a perfect emulsifier, making it a little less stable than a traditional mayonnaise.
For the past year or so, I've been hearing a lot about aquafaba, the protein-rich liquid found inside a can of chickpeas. It's pretty amazing stuff—you can whip it into stiff peaks like a meringue, use it to leaven pancakes and waffles, or make light sponge cakes, all without any eggs at all.
You can also use it to make mayonnaise. Or so they say.
I tried making mayonnaise with it the way many recipes instruct you: replace the egg in a traditional mayonnaise with three tablespoons of the protein-packed liquid. It works. Sort of.
It's possible to make a thick emulsion if you are very careful with the rate at which you add your oil, but the chances of your mayonnaise breaking are much greater than with a traditional mayonnaise. Moreover, the finished product is much looser than an egg-based mayo. It has the characteristic thin, shiny, slightly greasy appearance of an emulsion that's hanging on by the skin of its teeth (or should I say the skin of its legume?).
Why do eggs work better than chickpeas? Eggs are remarkable emulsifiers because they emulsify in two distinct ways. The first is physical, and the second is chemical.
Mayonnaise is an emulsion of oil and water, and, like all emulsions, it is inherently unstable. Oil molecules are physically repulsed by water molecules, making it very difficult to get them to coexist harmoniously. They naturally want to separate. To get them to combine, you need to add an emulsifier.
Physical emulsifiers work by adding viscosity to the liquids. The more viscous a liquid, the less it flows, and the more slowly individual oil and water droplets come into contact with each other, helping the whole thing stay in suspension. Honey, sugar, pounded nuts, crushed basil in pesto—these are all physical emulsifiers that offer varying degrees of added viscosity.
Chemical emulsifiers work differently. These are molecules that have one hydrophobic (oil-loving) and one hydrophilic (water-loving) end. Like a finger trap, they force oil and water to get along. This is how lecithin, a chemical found in abundance in egg yolks, works.
Chickpea liquid offers physical emulsion properties, but not chemical ones, making it less stable than eggs. The solution turned out to be super simple. I already had it in the bag, or, in this case, the can: just add a few of the actual chickpeas.
By adding just a dozen chickpeas to three tablespoons of liquid and blending it together with lemon juice, mustard, and garlic, you end up with a base for your mayo that's thick enough to form an ultra-stable emulsion even without the aid of chemical emulsifiers.*
* Though I do wonder if adding a sprinkle of soy lecithin—a vegetable-based alternative to egg-based lecithin—would work.
Your mayonnaise ends up light, creamy, completely grease-free, and stiff enough to hold its shape when you mound it up, but loose enough to spread easily over a sandwich. I'm not tasting it side by side with real, egg-based mayo because I'm still staying vegan this month, but I'd put it up against any homemade mayo out there (and yes, it'll blow any store-bought mayo out of the water). Best of all, it takes only two minutes to make.