To make a successful mayonnaise you need only remember two pieces of advice: none of the ingredients, not even the bowl in which it is made, should be chilled. If you have added the oil too fast you can rescue it by adding a dessertspoon of lukewarm water and whisking rather fast. So, to make mayonnaise all you have to do is put the egg yolk, the mustard, the juice of half a lemon and a little salt in a bowl. Mix them well and forget them for 5 minutes. Then add the oil in a thin stream, whisking all the time until all the oil is incorporated. Add the rest of the lemon juice. That’s all.
Add the watercress purée to the mayonnaise.
Put the cream in another bowl and whisk until thick. Season with salt. Mix the cream and the watercress mayonnaise together. Drain the whole watercress leaves (1) and dry them on a towel or kitchen-paper. Fold them into the mayonnaise and cream mixture. Add a pinch of cayenne pepper and keep the sauce in a cool place. Serve in a sauceboat.
© 1979 All rights reserved. Published by Macmillan.