Add all ingredients to container of immersion blender (or wide mouth mason jar).
Place blender directly over the egg and hold in place touching the bottom of the container.
Keeping the blender touching the bottom of the container, turn it on and mix until the oil stops incorporating.
Slowly raise the blender from the bottom of the container, maintaining the vacuum, to incorporate the rest of the oil.
Once the vacuum seal is broken, mix up and down a couple of more times and you're done.