For the curry mayonnaise, stir the cornflour and soup powder into the water, then bring to the boil briefly. Stir vigorously with a whisk to avoid lumps. Allow to cool.
Mix the egg yolks at room temperature with the cooled mixture and a good dash of vinegar and the mustard for about 5 minutes.
Then very slowly pour in the oil, stirring constantly, and mix until you have a thick sauce. Finally, season the curry mayonnaise with curry powder and Worchester sauce.