In the Whip 'N Mix Chef, combine the mustard, egg yolks, salt, pepper and 45 mL/3 tbsp oil, cover and whip on gear I for 10 sec.
Attach the funnel to the cover then pour in the remaining oil while whipping constantly on gear I.
Add the vinegar through the funnel, switch to gear II and whip for 10 sec.
If you like firm mayonnaise, you can stop here. If you like creamier mayonnaise, add 15–30 mL/1–2 tbsp water through the funnel and whip on gear II for a few seconds. Store in liquid-tight container in fridge for up to 5 days.