Secure the bowl by wrapping a towel around the bottom. That will keep it from jumping around when you whisk. Even better would be to place the bowl in a small pot. Add egg yolk to bowl. Add a squeeze of lemon juice to the yolk. Then measure a cup of vegetable oil – you may not use the whole thing – in a cup that makes it easy to pour slowly. While continuously, vigorously whisking, drizzle in oil in the slowest stream you can. Can’t stress these two next things enough –
Slowest stream you can
Don’t stop whisking
You’re forming an emulsion and if done improperly, it will break.
If your mayonnaise breaks (looks like an oil slick), put half an egg yolk into a new bowl (approximate) and slowly drizzle in the oil slick. If you go slow enough, should come back together.
Oil thickens. Egg yolk/lemon juice thins. So once you’ve drizzled enough oil in to get your desired thickness, (even if you haven’t used the whole cup), stop and season with salt to taste. Will keep in fridge for two weeks.
sub in 1/4 cup of the vegetable oil for olive oil, or garlic oil, or sundried-tomato oil
Add chopped chipotles, or herbs, or lemon juice, or dijon.