Put the egg yolks, mustard and a tablespoon of oil in the mini bowl.
Blend for 20 sec., then slowly drizzle in half the remaining oil via the feed tube, increasing the flow as the mixture thickens.
Add the salt and pepper then, with the machine still running, pour in the rest of the oil.
Wait until the very last minute to add the vinegar.
All the ingredients must be at room temperature.
To achieve a softer consistency, use whole eggs.