Hollandaise sauce ( or ; ) is an
emulsion of
egg yolk and
liquid butter, usually seasoned with
lemon juice,
salt, and a little
white pepper or
cayenne pepper. In appearance, it is light yellow and opaque, smooth and creamy. Its flavor is rich and buttery, with a mild tang added by an acidic component such as lemon juice, yet not so strong as to overpower mildly flavored foods.