Filet Mignon Dinner: Step 3a Bearnaise sauce
First you make an Hollandaise and then you put in tarragon, vinegar, shallots, chervil and you are done.
Here's how I do it. I melt 3/4 lb of butter in the microwave with tarragon, vinegar, shallots, chervil. Add rice wine vinegar to the mix, 1 tsp. You can clarify your butter. I don't. You may add lemon, 1 tsp, or you may use 2 tsp vinegar. I use about 1/2 a shallot, a couple of springs of fresh tarragon, and some chervil. (Using the microwave is quick and dirty but it comes out great.)
Next, I take 5 egg yolks and scramble them in a pan above a bain marie, a pot of hot water. Get the water boiling, turn it off, and whisk the yolks to warm them on the bain marie. Strain the butter. Then before you get scrambled eggs, you must start adding the butter and other liquids.
Heat the yolks above 160. My rule of thumb is I want to be able to touch the pan I am using to make the sauce. If it gets too hot, take it off the bain marie. However, if you turn the bain marie off and never turn it on again, you wont have a problem.
Slowly add the butter to the yolk while whisking. You don't have to go as slowly as when making mayonnaise but don't rush it or the emulsion will break. Don't over heat or you'll be scrambled eggs and the emulsion will break.
Finally, I season with white pepper finely ground and Fleur de Sel, sea salt from Brittany. Or you can use Sel Marin de Guerande, which is grey but only lightly grey. I try not to add something that will discolor the sauce.
Then, what I do, is put it on my stove ledge with a pot holder underneath to keep it warm. I'll thicken even more and you have to whisk it before serving. Voila, you have a sauce béarnaise. An easy to make one, to boot.