Ingredients: (makes about one cup)
1 egg yolk
1 T lemon juice (lime juice or white vinegar will work too if that's all you have)
1 T water
1 t dijon mustard
1 cup Vegetable oil
Combine the egg yolk, lemon (or lime) juice, water and dijon mustard into your cup. If you have a tall measuring cup like the one in the photo, that is ideal for using the immersion blender.
Pour the oil into the cup next.
Place the head of the blender in the cup, and turn it on, moving it around slightly as needed. You may need to stop every once in a while to scrape the edges or stir. The total blending time is only about one minute.
You will see the mixture become solid and in the end it will be the same texture as the mayo you buy at the store! Season with a little kosher salt, and you are done. So easy!