Take an egg yolk. Add half a teaspoon of Dijon mustard. Teaspoon of olive oil. Mix. Then as you continue mixing vigorously, very slowly add some neutral oil, preferably peanut or sunflower but go with generic veg oil if it's all you have. Stop when it's not a liquid anymore.
This is mayo. What you get in stores and 95% of restaurants is not.
Yes I'm a food snob.
I don't know exactly how this works, but I think you'll be held in contempt when you get a subpoena and decide not to show up.