Start by making the sabayon, egg yolks, water and a pinch of salt. Mix and cook slowly over a double boiler until the yolks have tripled in volume and have thickened.
Off the heat, slowly drizzle in your clarified butter, being sure to fully emulsify between each ladle. For every yolk, add 2-3 oz clarified butter.
Make the reduction by adding the shallot, crushed pepper corns, tarragon stems, white wine and vinegar. Reduce by 2/3, combine with sabayon and strain. Adjust the sauce with warm water if too thick and salt if needed.