Once all the Base Ingredients are incorporated, measure out the oil into a liquid measuring cup. Turn the food processor on and slowly add the oil, starting with just a few drops at a time. After a tablespoon, you can add the oil a little faster (a drizzle), but never pouring the oil in. This will slowly incorporate the oil into the egg yolks, making a fluffy/pillowy sauce vs a broken sauce (were the oil looks like rain drips with splotches of egg yolk swimming in it.