As simple as it may sound, it is very easy to make mistakes so that the oil never gets incorporated into the beaten egg yolks. The secret is in the slow pouring and continuous mixing.
The color of the mayonnaise is affected by the kind of oil used. If olive oil is used, a deeper-colored mayonnaise is formed. If a neutral-colored oil is used, the mayonnaise is a very light cream in color. It all depends on your preference. The Spaniards use olive oil in their mayo; the Japanese use soya oil. In this post, I used a mixture of olive oil and pure coconut oil.
The most convenient way to make mayonnaise is to use a blender or food processor. In this post, I used a wire whisk and mixed everything by hand just to to show that neither blender nor food processor is necessary.
To make about a cup of mayo, start with two egg yolks and the juice of half a lemon. Mustard is not a necessary ingredient but I like mustard so I added half a teaspoonful of whole grain mustard. If you like mustard too, you can use plain yellow mustard if whole grain is not your thing. I also like garlic so I added about a quarter teaspoonful of grated garlic. Then, a quarter teaspoonful of salt and pepper.
In a mixing bowl, whisk together the egg yolk and lemon juice, and whatever add-ons you like.
Pour in the oil, drop by drop at first, whisking the mixture in the bowl as you pour.
When the mixture thickens a bit (check that the oil does not separate from the yolk mixture), you can pour the oil in a thin stream, still whisking vigorously as you pour.
How much oil? For two egg yolks, about a cup although I go by texture rather than measurement. I stop pouring when I get the consistency that I like.
You can adjust the seasonings at this point. Maybe, you’d like to add the juice of the remaining half of lemon. Or, perhaps, more salt and pepper. If you like sweet version a la Japanese mayo, you can add a bit of sugar. Whatever you add, mix and taste after adding every ingredient.
To store, transfer the mayonnaise into a jar or container with a tight lid and keep in the refrigerator. Because homemade mayonnaise uses raw egg yolks and no preservatives, it is best to use it within two days.