Mayonnaise is an emulsion in which egg yolk helps hold tiny oil droplets in a water-based mixture. The first oil additions need patience. Use pasteurised egg yolks or a suitable pasteurised egg product because this method does not cook the egg.
Step by step
Prepare a stable yolk mixture
Use a tested mayonnaise recipe for the quantities. Whisk its pasteurised yolks, mustard, acid and other starting ingredients in a clean bowl. Set the bowl on a damp cloth so it does not slide.
Begin with drops of oil
Whisk continuously while adding just a few drops of oil at a time. Make sure each addition disappears into the mixture before adding more. Do not pour a puddle of oil into the bowl at the start.
Increase to a thin stream
Once the mixture thickens and looks uniform, add oil in a narrow stream while whisking. Slow down if oily patches appear. Use the recipe’s small liquid additions if the mayonnaise becomes too thick to whisk comfortably.
Image by JustRecipesSeason and refrigerate
Adjust the finished flavour with the recipe’s acid and seasoning. Transfer to a clean covered container and refrigerate promptly. Follow the recipe and egg product’s storage instructions; homemade mayonnaise does not have a commercial jar’s shelf life.
How to approach a split batch
For a safely handled batch that has separated, start a clean bowl with another pasteurised yolk as your recipe allows. Whisk the broken mixture into it very slowly, beginning with drops. Stop if it will not come together. Acid does not reliably make raw unpasteurised egg safe, and re-emulsifying cannot rescue mayonnaise left unrefrigerated too long.
