of the divide—keep it away from the bread at all costs—but
after having been slowly weaned onto it by means of
excellent homemade versions, I’ve come to love it so much
that I’ll even abide the blue-topped jarred stuff from time to
time. At its best, it is creamy, tangy, and light on the palate,
with the ability to add richness to a dish without weighing it
down. More often than not, though, it’s either a poorly
made, heavy, greasy, underseasoned goo or overly sweet,
gloppy stuff from a jar. OK in a pinch, but hardly something
you’d want to, say, dip your asparagus into or use as the
base of a Caesar salad dressing or tartar sauce.
So what is it that transforms two ingredients—egg yolks
and oil—that are kind of icky (that’s a technical term) to eat
on their own into a luxuriously rich, tangy, creamy spread
that’s not greasy in the slightest, despite consisting of over
75 percent oil? It’s called an emulsion, and it’s one of the
most important concepts to understand in the kitchen. An
emulsion is what keeps your vinaigrettes clinging to your
lettuce. It’s what keeps your cheese smooth and stretchy
when it melts (we touched a bit on cheesy emulsions in
Chapter 7). An emulsion is, quite literally, what keeps your
gravy boat flowing. Let’s take a closer look at this fine stuff,
shall we?
Mayo Basics
In its loosest definition, mayonnaise is a flavored emulsion
of minute particles of fat suspended in water. The tiny
globules of suspended fat have a very difficult time flowing
around once they are separated by a thin film of water,
which is what gives mayonnaise its viscosity. For the record,