Just a few tips will make preparing aioli easier. First, be sure all the ingredients are at room temperature. Begin by making an emulsion with the egg yolk, mustard and just 1 Tbs. of the oil, then add the remaining oil very slowly and whisk constantly. Aioli can also be made in a blender or in a small food processor fitted with the metal blade using this same basic method, with the motor running as the oil is added.