Bypass the whole egg yolk and whisk situation by making it in a pan. Melt 25g of butter over a medium heat and add a finely chopped shallot. Cook for five or six minutes then add 1 teaspoon of white wine vinegar. Cook for another couple of minutes then stir in 100g crème fraiche, 1 teaspoon of Dijon mustard, 1/2 teaspoon of capers and a small bunch of tarragon, chopped. Reduce the heat and cook gently for two or three minutes until simmering, seaosn then serve. If you do want to try making it the traditional French way, you may find our video guide helpful.