Traditionally a dip for vegetables and salt cod, aioli also goes well with lamb or chicken.
Put the first 4 ingredients in a blender or food processor, and process on high speed for 10 seconds. With machine on, add oil drop by drop until emulsified, then in a trickle to finish. Season to taste.
This recipe for aioli contains raw egg, which should not be used in food prepared for pregnant women, babies, young children, the elderly, or anyone whose health is compromised.
The key to preventing the sauce from separating is to have all the ingredients at room temperature. Be sure to use the freshest eggs and the plumpest, least blemished garlic you can find.