Step 1

Place egg yolks in a tall narrow container that the blender stick fits in all the way to the base.

Step 2

Add water, lemon juice, cayanne pepper and salt. Blitz briefly to combine.

Step 3

Melt butter in a heatproof jug until hot (be very careful to ensure it doesn't explode if using microwave!). If you use a stove, pour into a jug.

Step 4

Let butter stand for just 15 seconds or so until the milky whites settles at the bottom of the jug. (Note 2)

Step 5

With the blender stick going on high, slowly pour the butter in a thin stream into the eggs over around 45 seconds. Leave behind most of the milky whites in the butter - about 1 1/2 tbsp. (Note Once all the butter is in, the sauce should be thick, creamy, smooth and pale yellow.

Step 6

Now blitz for a further 10 seconds, moving the stick up and down.

Step 7

Thickness: If too thick, mix in warm tap water 1 teaspoon at a time.

Step 8

Salt adjustment: Add a touch of extra salt if using for something non salty like asparagus, leave salt as is if pairing with salty foods like Eggs Benedict, steak, fish.

Step 9

Lemon adjustment: Make it slightly more tangy that you want if using for something like Eggs Benedict, steak or salmon (because it's diluted when you eat it, and also balances the rich food). But make it perfectly lemony to your taste if using for something like Asparagus.

Step 10

Using: Use immediately, or keep warm until required - if covered and wrapped in a tea towel, it will stay warm for 15 minutes. Use warm or at room temperature. Use warm tap water for loosening. See note for storing and reheating.