Aioli is simply a mayonnaise made with garlic and olive oil. Using an immersion blender makes the process super-easy and the result works well as a light dip for vegetables or as a spread on breads and toast.
Once you have the basic process down you can take this dip in many directions. Leave out the garlic and use only canola or vegetable oils and you have a standard mayonnaise. Add some ginger, replace the water with soy sauce, and use some sesame oil and you have an Asian-themed dip. Incorporate some chipotles in adobo sauce or cayenne pepper for a spicy dip. The possibilities are really endless.
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Combine everything except the oil in a bowl or measuring glass. Blend briefly with the immersion blender to combine. Slowly pour in the oil while blending until the aioli comes together and all the oil is combined.
The aioli will hold together for several hours but if it starts to separate you can briefly re-blend it until it comes back together.