If you have an immersion blender: Add your egg, 1 tablespoon of Dijon mustard, and the canola or neutral vegetable oil to your immersion blender cup or a cup/jar that is a little bit larger than your blender stick. Put blender on the bottom of the cup and start blending on low. Once you start to see things thickening, you can start to make a slight up and down movement. I like to stop every so often and kind of stir things around with the stick while the blender isn't running. But you should be able to get something that resembles mayonnaise texture in just two or three minutes of blending. Once done you can skip to the MUSTARD step.

If you do not have a blender, get ready to whisk: Grab a medium mixing bowl and a whisk.

Whisk the yolks, salt, and lemon juice (if using) until it all is a bit frothy. Slowly trickle oil into the bowl while whisking. Add more oil very slowly whisking the whole time. You will start to see things getting a bit thicker and at that point, you can add more oil.

Once things start to look more like a yogurt texture you can increase the flow of oil. But you still want to continue vigorously whisking. If you ever start to get a texture where your mayo looks like it's curdling, you need to stop adding oil until your texture binds back together.

You can stop whisking when you've used all your oil and the texture of your mayo is smooth.

Mustard: add 2 more tablespoons of Dijon mustard to the mayonnaise and stir everything up until it is all combined.

Put the mayonnaise into a jar or sealed container and store it in the fridge for no more than two weeks.