Here's our formula for great eggless mayonnaise.
Eggless mayonnaise sounds like an oxymoron, and every mayo alternative we’ve ever tried has been a far cry from the velvety richness of the real deal. But when we stumbled across an unusual “milk mayonnaise,” made with just milk, lemon juice, garlic, pepper, and oil, on the blog of food writer David Leite, we were intrigued. It turns out that the casein proteins in milk perform a stabilizing function similar to the lecithin in egg yolks: Casein proteins allow droplets of oil to remain suspended in the milk, creating a creamy texture. We tweaked Leite’s version to make it even more foolproof, adding mustard (another good emulsifier) for extra stability and upping the amount of lemon juice, as citric acid denatures the milk’s casein proteins, increasing their emulsifying properties. Our egg-free emulsion is just as billowy and creamy as regular mayo but with a lighter, cleaner taste that we even prefer in some applications.
To make it, whisk 1⁄3 cup milk, 1 teaspoon mustard, 1 teaspoon lemon juice, one small clove of garlic (minced), 1⁄4 teaspoon salt, and 1⁄8 teaspoon sugar in a tall-sided clear container just wide enough to fit an immersion blender. Pour in 3⁄4 cup of vegetable oil and place an immersion blender at the bottom of the container. Blend on low speed until a thick emulsion forms in the lower half of the container. With the blender still running, slowly pull it up to incorporate the rest of the oil. Serve immediately or refrigerate for up to one week in an airtight container.