Avocado Mayo

Place egg yolk, mustard, lemon juice and salt into a narrow jar with a wide lid to accommodate the immersion blender.
Place the blender in jar so that it touches the bottom.
Turn blender on. Slowly drizzle in the avocado oil. You will see mayo thicken up almost immediately.
Keep the blender at the bottom of the jar for 20-25 seconds, if needed, move the blender up and down the last few seconds.
Store in a container in the fridge for up to a week.