Add all the ingredients to the jar (order doesn't matter)
If the mustard, salt, egg, and lemon juice haven't settle to the bottom of the jar then push them to the bottom with your immersion blender.
Place your immersion blender at the bottom of the jar, making sure to cover the egg. Start blending and begin pulling up slowly as the oil beneath the blender blade turns white.
You are done once all the oil has turned to mayonnaise and there is no visible oil left.
