It's lactofermented. So you can use the remaining whey from the production of cheese or labneh or other fermented kinds of dairy. One teaspoon is enough. I've never done fermented mayo but your recipe seemed like a good fit for that in my mind.
I saved a recipe link from YouTube a few months ago because it seemed easy and cool
I don't do this because I'm poor and don't want to introduce seed oils in the mix. Maybe you want to use avocado oil or coconut oil