Hmmm…. While it is not one of the classic French "mother sauces," we expected to find a single recipe - perhaps with somewhat different quantities of ingredients - but certainly with the same ingredients and the same basic procedures among various cookbooks. We are flummoxed. Even among the old French cookbooks, there are differences.
Béarnaise Sauce is a butter- and egg-based sauce flavored with (at least) vinegar, shallots, tarragon, and pepper. It was traditionally served with assertive meats or fish.
The biggest difference in ingredients is that some recipes direct you to use wine in the initial mixture alongside wine vinegar, while others omit the wine, and some recipes add chervil to the tarragon. We would think the wine-less recipes were silly, except that it is Escoffier's recipe that omits the wine. We would think the recipes with chervil were a modern variation, except that Escoffier's recipe includes chervil. Some recipes add a little lemon juice. Others use thyme and a bay leaf. Some recipes allow you to use an onion instead of shallots, but those are clearly from the days when shallots were an exotic and hard-to-find ingredient in this country. You may not use onions to make a Béarnaise Sauce.
The biggest difference in process is that a few of the old French recipes have you beating room-temperature butter into the egg yolk mixture, while more recent and Americanized recipes direct you to use melted or [link] clarified butter. Some recipes also direct you to strain the sauce at some point in the process; others do not.
With so much confusion, how are we to tell you the proper way to make the sauce? Once again, we bite the bullet and make a choice on your behalf. Yes, overzealous cooking school students will write us scathing e-mails, telling us, "that's not how you make Béarnaise Sauce, dude," but, as always, we will soldier on, withstanding the relentless pressure of a deeply fragmented cooking world.
Enough wallowing. Here is a recipe that will either please everyone or no one. It is similar to Escoffier's recipe with wine added.