Place the peppercorns and vinegar in a small stainless steel saucepan and reduce to one third. Remove from the heat and add 1 tablespoon of cold water. Allow to cool.

Whisk in the egg yolks in a bowl and add the reduction. Place the bowl over a simmering pan of water and continue whipping until the yolks form ribbons.

Gradually add the warm melted butter whisking constantly until thoroughly combined.
Add the lemon juice, shallots and tarragon and season to taste with salt and freshly ground black pepper.