Add the aquafaba, mustard, salt and vinegar to a tall container and blend for about 20 seconds (I like to blend on some frozen peas to keep the mixture cool)
Very slowly start to add the oil (the mixture needs to emulsify so make sure the oil is constantly blending in with the mixture and if it starts to split stop adding oil and make sure it's completely blended before starting to add more)
Once all of the oil has been blended, add the virgin oil and blend.
At this stage the mixture should be smooth and thick
Add maple syrup (and lemon if using) and check for taste
Refrigerate in air tight container for up to a week.