put the egg yolk in a large bowl
add vinager, mustard, salt and sugar to the yolk
whisk until completely desolved
add a small gluck of oil and whisk until smooth and desolved
add a small gluck of oil and whisk until smooth and desolved repeat this 7 more times
now while whisking strongly add a continuous stream of oil .if in doubt stop the oil and keep whisking until desolved.keep doing this process until the mayonnaise becomes thick.go on a little further so it is really thick now taste and add salt and ground pepper to taste.
from this point put the mayonnaise in the fridge and cool for at least an hour
Last have fun from this mayonnaise you can make any sauce you like.