In a saucepan, combine the dry white wine, white wine vinegar, shallot, and tarragon leaves. Bring to a simmer and cook until reduced to about 2 tablespoons.

Strain the mixture into a bowl, discarding the solid ingredients.

Whisk in the egg yolks and lemon juice until well combined.

Place the bowl over a pot of simmering water (double boiler) and whisk continuously until the mixture thickens.

Gradually add the melted butter or ghee while whisking until fully incorporated and the sauce is creamy.

Stir in the finely chopped tarragon and season with kosher salt to taste.