It's a common offering seen on many cafe menus - fries with aioli. While usually this is just a mayonnaise with some garlic blended through it, true aioli is another animal. There is nothing wrong with making a garlic mayo but, if doing so, you will achieve a better result by using roasted garlic as opposed to raw.
Aioli is a traditional Provencal sauce made with garlic, olive oil, lemon juice and egg yolks. The Spanish Catalan version is named allioli. Many recipe variations exist - mustard may be added, in Catalonia pears can become an ingredient.
The name aioli comes from Provencal words "alh" meaning "garlic" and "oli" meaning "oil". It is an emulsion sauce, like mayonnaise.
1. Smash 6 fresh, peeled garlic cloves to a paste in a motor and pestle.
2. Whisk into this 2 egg yolks and, if you like, a teaspoon of grain mustard.