Instructions

To make the reduction:
In a stainless steel lined pan, melt the butter, add the chopped shallots and soften.

Combine the shallots, vinegar, peppercorns, and tarragon in a heavy-based saucepan and simmer over medium high until 4 tblsp of liquid remains.

Strain and discard the solids. A simple rule to follow is: "The volume of the reduction should equal the volume of the yolks."

Put the yolks into a stainless steel bowl and beat them frothy with a whip. Beat the reduction into the yolks over low heat in a double boiler, or over hot water.
They should become thick and creates a ribbon from your whip to the bowl.

Now beat in the melted or soft butter, slowly at first. When the sauce becomes thick, like a mayonnaise, take it off the heat and continue beating as the bottom of the bowl may have enough heat to break the sauce.
If it breaks, just start with a fresh egg yolk in a new bowl and add the broken sauce by whipping. It comes back fast.

Finish the sauce with some fresh tarragon.

You should taste this sauce carefully. If it is too acidic, thin it a bit with white wine. If it is too herbal, thin it with some hollandaise. It probably won't need salt, but if it needs pepper, use cayenne. It should be hardly noticeable peppery taste. Serve the sauce warm. Put any extra into a gravy boat.

You should make this sauce within 15-30 minutes of serving, although the reduction, can be done well ahead of time