Combine the lemon juice and white wine in a small saucepan and bring to a simmer. Reduce until you have two tablespoons of reduction left, then remove from the heat and set to one side. Place the butter in a small saucepan and melt over a low heat. Pour the golden liquid butter into a jug and discard the white milk solids. Combine the egg yolks and reduction in a heatproof mixing bowl and set over a saucepan of gently simmering water. Whisk the mixture over the saucepan for 4 to 5 minutes until you have a fluffy sabayon; you will know you've reached this stage when the whisk leaves trails in the mixture. Remove from the heat and whisk in the clarified butter in a slow steady stream until you have a thickened sauce. Season to taste with salt, pepper and an optional pinch of cayenne. Serve immediately.
