Step 1

Place the vinegar, wine, eschalot and peppercorns in a small saucepan over medium heat and bring to the boil. Boil, uncovered, stirring occasionally, for 3 minutes or until the liquid is reduced to about 2 tablespoons. (This mixture is called a reduction. The volume of the liquid is reduced by evaporation, leaving a mixture that is slightly thicker with a more intense flavour.)

Step 2

Strain the vinegar mixture through a fine sieve into a small frying pan. Discard eschalot and peppercorns.

Step 3

Place the frying pan over low heat. Add the butter, 1 cube at a time, whisking constantly and adding another cube only when the previous cube has been completely incorporated. (It's important to chill the butter before adding it to the vinegar reduction. If the butter is warm it may melt too quickly, making it harder to incorporate into the liquid and causing the mixture to split.)

Step 4

Once all the butter is incorporated (this will take about 8 minutes), remove from heat. Whisk in the lemon juice and season with salt and pepper. (We used unsalted butter for this recipe as it is easier to taste and season the sauce to your liking at the end.)