Bearnaise Sauce Recipe

First, fill and boil your kettle, then melt the butter gently over a low heat. Next, put the white wine, the vinegar, the shallot and the peppercorns into a saucepan and bring up to the boil. Once boiling, turn the heat down and simmer until the liquid has reduced by about half. Using a sieve to strain out the peppercorns, pour the mixture into a bowl. Take a clean pan, large enough for the bowl to sit on (but not in) and half-fill it with hot water from the kettle, then bring it to the boil, reducing it to a simmer. Add the egg yolks to the vinegar mixture in the bowl, and whisk them in, then add the lemon juice. Set the bowl carefully over the pan of simmering water, and whisk again until the contents start to thicken and become lighter in colour. Pour in the melted butter in a slow, steady stream, whisking as you go. When all the butter has been incorporated into the sauce, add the chopped Tarragon leaves and season to your taste with the salt and pepper. Turn off the heat under the water pan; leave the sauce-bowl sitting over the warm water until you are ready to use it.