Dice the shallot roughly chop half the tarragon (finely chop the rest and set aside)
Heat the white wine, white wine vinegar, shallot pepper and the roughly chopped tarragon in a small saucepan over a medium heat until it is simmering.
Simmer for about three minutes, until the liquid has reduced by half, turn the heat off and let to cool for 6 minutes (or longer if you want)
Stain the mixture through a sieve into the blender, pushing down on the solids in the sieve to get as much or the liquid out.
Add the yolks to the blender
Roughly chop the butter and melt it in the microwave for about 1min 20sec, in bursts, stirring between (e.g, 40 secs, stir, 20 secs, stir, 20 secs).
Put the lid on the blender and remove the spouty thing in the middle of the lid, start blending at a medium high speed, slowly pour the hot butter through the hole in the lid until all that is left in the jug is the milky solid stuff, turn blender off.
Add the finely chopped tarragon and a pinch of salt and blend on a medium speed for 10 seconds and serve over steak or pretty much any protein that is begging for a sauce.
