Tarragon-Infused Hot Emulsified Egg Yolk Sauce for Fish

This sauce is particularly convenient because the egg yolks are cooked ahead of time and then blended with flavorful liquid just before the restaurant service or the dinner party. The egg yolks can be kept, sealed in their sous vide bag, in the refrigerator for up to five days, and used as needed. The proportions given here contain a rather large percentage of egg yolks, creating a thick and unctuous sauce, but the sauce can be thinned with additional liquid to arrive at the desired consist