I got a question from Bobbi:
“Can you still consider it vegan if you make it with mayonnaise? Doesn’t mayonnaise have milk and eggs in it?”
The answer is that traditional mayonnaise is made with eggs and oil, but no dairy.
The egg provides lecithin, which acts as an emulsifier. Emulsifiers help to combine ingredients that do not like to live together, like oil and water or vinegar, so that they become one harmonious unit.
Other emulsifiers are normally in salad dressings, the other place you commonly need to combine oil and vinegar or other non-oily liquid. Those include mustard or fruit and vegetable purees.
Since vegans take out the eggs, the other place you can find lecithin is in soy. So we use soymilk, plus mustard, to emulsify the oil and acid (usually vinegar and/or lemon juice).
You can buy commercial vegan mayonnaise, or you can try the recipe I posted here.