1. Add all the ingredients except oil to a high-speed blender or a food processor.
2. Turn the machine on and very slowly pour the oil through the feed tube.
3. Blend until the oil is combined and mayonnaise has thickened. Turn the machine off when you reach the desired thickness. Make sure not to over blend, as that can cause it to break.
4. Store in an airtight container in the refrigerator for up to a week.
Notes
If using an immersion blender, add all the ingredients except oil to a tall cylindrical container. Combine the ingredients using an immersion blender at medium speed, until the mixture becomes frothy. Slowly begin to pour oil into the mixture until your mayonnaise has thickened.