Measure all ingredients and prepare for use
Peel and finely chop the shallot.
Place in a sauté pan with the peppercorns, white wine vinegar and about 100ml water.
Bring to the boil and bubble until reduced by two thirds. Remove from the heat and allow to cool.
Put the butter in a small saucepan and allow to melt over a low heat.
Let the butter melt over low heat.
When the butter separates, remove from the heat.
Pour the butter slowly through a fine sieve.
Place the egg yolks in a heatproof bowl and pour in the reduction through a fine sieve.
Set the bowl over a pan of hot water and beat with a whisk until thick and creamy.
Remove from the heat and add the butter in drops, then a thin stream, stirring constantly.
Keep whisking until the sauce is thick and glossy. Season with salt and lemon juice.