Instructions

1. 1
   In a large bowl, beat the egg yolk with a wire whisk for about a minute.
2. 2
   Then add the mustard, salt, and half the lemon juice. Whisk for another minute - the mixture should thicken very slightly.
3. 3
   Then, very slowly, add half the oil with one hand whilst whisking with the other.
4. 4
   Start drop by drop, incorporating each drop before adding the next, and build up to a trickle.
5. 5
   Keep going until the oil is whisked in.
6. 6
   Add the rest of the lemon juice, whisk to combine.
7. 7
   Add the rest of the oil in the same manner as before.
8. 8
   Keep going until all the oil is whisked in.
9. 9
   If desired, stir in flavourings such as crushed garlic, or use the mayonnaise as a base for other sauces.