How to Make It
Vinegar-Water. Place water and vinegar in the bowl of a food processor.
The water is what the oil will be suspended in, so start here. Acid (such as vinegar or citrus) behaves the same way as water, and its tart flavor will balance the rich spread.
Egg Yolks, the Emulsifier. Add egg yolks and salt; pulse to combine.
Egg yolks contain lecithin, which resembles both oil and water molecules and can connect to both. The salt boosts flavor and makes eggs more viscous, which helps prevent separation.
Oil and Agitation. With food processor running, slowly pour oil in a thin stream through food chute.
The key to marrying oil and water is to start slowly and agitate constantly. The mixing motion creates tiny droplets of oil and bubbles of air that the emulsifier (egg yolks) surrounds and keeps evenly distributed in the vinegar-water mixture. If the oil is added too quickly, the emulsifier can't join the water and oil molecules, and the mayonnaise will separate.
Why Make Mayo? Prepared and homemade mayonnaise are similar in calories and saturated fat. Flavor, however, is incomparable: Homemade mayo tastes richer and will likely go a longer way toward satisfying you. And most prepared mayos contain added sugar, artificial preservatives and additives, thickeners, and twice as much sodium as ours.