Béarnaise Sauce

Instructions

1. Melt 60 g of unsalted butter in a small pan over the lowest heat without stirring, about 5 minutes. Skim the white foam from the surface, then pour the clear golden fat carefully into a small jug, leaving the milky solids in the bottom of the pan. Set the clarified butter aside somewhere warm, around 50C, it must not be hot enough to scramble the yolk.
2. Put 1 small shallot, finely chopped, into a small stainless steel or enamelled pan with 2 tbsp of white wine vinegar, 2 tbsp of dry white wine, 4 coarsely crushed black peppercorns and the reserved tarragon stalks. Bring to a simmer over medium heat and reduce for 5-6 minutes, until only about 1 tbsp of syrupy liquid remains.
3. Strain the reduction through a fine sieve into a heatproof bowl, pressing the shallot and stalks well to extract every drop, then leave it to cool for 2 minutes until just warm.