Place water, vinegar, salt and pepper in a small saucepan and reduce by two thirds.
Remove from the heat and place on the back of the stove.
Place the remaining water, egg yolks and the reduction into a stainless steel bowl.
Cook over medium heat while whisking constantly.
When the yolks turn a light yellow and thicken slightly you can begin to add the melted butter gradually while whisking constantly.
If it begins to thicken add a few drops of warm water occasionally as needed.

Correct seasoning with salt and a few drops of lemon juice.

Pass through a fine strainer or cheesecloth and keep warm to prevent the sauce from separating.

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