To make Lemon Beurre Blanc
Put half a shallot finely diced into a pan with 2 tbs of dry white wine and 1 tbs of white wine vinegar. Bring it to the boil and reduce until almost all the liquid has evaporated. Add 50 mls of water and gradually whisk in 120g of chilled diced butter to make a smooth creamy sauce. Add lemon juice to taste and keep warm by placing the pan in a bain-marie (or a bowl full of very hot water) until required.