To make the hollandaise sauce: place the vinegar, water, shallots, herbs and peppercorns in a saucepan and reduce the liquid to about a tablespoonful.
Strain and put aside.
Melt the butter and simmer it for 5-10 minutes.
Take off the heat, leave to cool a little, then pour off the pure fat where it has separated from the whey and discard the whey.
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