Prepare all the ingredients.
Put the mustard in a bowl. Separate the egg whites one after the other and mix the yolks with the mustard.
Season with salt and white pepper (preferably).
Whisk in a rotating pattern to mix egg yolks with mustard. Pour the oil in gradually.
The oil will combine with the mustard and eggs, making a mayonnaise. Keep whisking until all of the oil has been added.
At last, whisk vigorously to thicken the mayonnaise. Add the vinegar (optional). To be used within 24 hours.
To make this recipe, some of these items will be required: