How To Make Mayonnaise
1. Put the egg yolk, pepper, salt, and mustard in a bowl.
2. Beat continuously and vigorously with a whisk, adding the oil drop by drop: this requires a great deal of patience, but it is the only way to obtain a light yet firm mayonnaise.
3. When the sauce has reached to desired density, all that remains is to add the vinegar (some people prefer lemon juice), again, a drop at a time.
4. Once the mayonnaise is ready, leave it to rest in the fridge for a couple of hours.