Traditionally, a beurre blanc consists of nearly equal parts white wine and good white wine vinegar reduced dramatically with shallot, held in emulsion with quite a lot of butter. Once the basic technique has been mastered, don't be afraid to experiment with new ingredients. Many modern variations exist employing any number of herbs and flavorings.
Correctly prepared, a basic beurre blanc should be creamy and tangy with a good savory component, pairing well with lean meats, particularly fish. I recommend it highly with a nice preparation of pan-seared halibut, seasoned simply with salt and pepper. What follows is a recipe for a simple, semi-traditional beurre blanc.
- For four portions, start with a cup of good white wine with a strong acidity (think dry aromatic white, preferably French, such as Pouilly-Fumé) in a non-reactive saucepan with the juice of one lemon and one or two very finely chopped shallots.
- Reduce the mixture to about two tablespoons, and don't be shy about letting it boil: it will not adversely affect the sauce. Once reduced, the shallot should still be fairly moist. If you're looking at a dry pan, there's a good chance your sauce won't hold.
- Reduce heat to low flame. If you want to increase the holding power of your sauce, you can add a tablespoon or so of heavy cream at this juncture, but every authority on traditional French preparation would disapprove.
- Begin to add smallish cubes of very good, very cold unsalted butter while whisking vigorously. From a technical standpoint, the sauce should stay under 200°F (95°C), so do some of the whisking off the flame. Whisk in one or two cubes and add more, and continue until you've added about 10 to 12 tablespoons of butter.
- Season with salt and white pepper and serve immediately. The sauce can be held in a vacuum container, such a Thermos, but I don't recommend it for long periods of time.
American chefs may try to enhance the presentation of the sauce by straining the shallot out before plating, but the French know better. If the shallot has been sufficiently chopped it has no deleterious effect on the texture of the finished product.