Ingredient

Beurre blanc

Beurre blanc is butter whisked into an acidic reduction until it becomes a pale, glossy sauce. There is no egg and no cream in the classical version — the emulsion is held by the milk proteins in the butter itself, which is why it is more delicate than a hollandaise and quicker to make.

How butter emulsifies itself

Butter is already an emulsion — roughly 80% fat with water and milk solids dispersed through it. Whisked cold, in pieces, into a warm acidic liquid, those milk solids act as the emulsifier and hold the melting fat in suspension.

The temperature window is narrow. Too cool and the butter does not melt into the emulsion; too hot and the fat separates out and pools. Somewhere around the temperature of a hot bath is right — warm enough to melt butter, nowhere near a simmer.

This is also why the butter must be cold and added a piece at a time. Each cold piece cools the pan slightly as it melts, which is doing useful work holding the temperature down.

The method

1. Reduce white wine and white wine vinegar with finely chopped shallot until only a couple of tablespoons of syrupy liquid remain.
2. Add a splash of double cream if you want insurance. It is not classical, and it makes the sauce considerably more stable — most restaurants do it.
3. Turn the heat to its lowest, or take the pan off entirely.
4. Whisk in very cold, cubed butter a few pieces at a time, letting each addition disappear before the next. Keep the pan moving.
5. If it looks like it is getting hot, lift it off. If it stops emulsifying, it has cooled too far — a few seconds back on the heat is enough.
6. Season, and strain out the shallot if you want it smooth. Serve within minutes.

Holding and rescuing

• It does not hold well. Twenty minutes in a warm place is realistic; a thermos extends that.
• The cream version holds much longer and is the practical choice for a dinner party.
• If it splits, take it off the heat and whisk in an ice cube or a spoonful of cold cream.
• If that fails, start with a tablespoon of cream or reduction in a clean pan and whisk the broken sauce into it slowly.
• Never let it boil. One boil and it is finished.

What to serve it with

White fish

The classic pairing. Turbot, sole, cod, halibut.

Asparagus and green vegetables

Excellent, and lighter than hollandaise.

Scallops

Particularly good, especially with a little of the searing pan juices whisked in.

Chicken

Works, though a pan sauce built on the same principle is usually better.

Beurre rouge

The same sauce made with red wine. Darker, sharper, for beef or oily fish.

The variations

Once the emulsion technique is in hand, the same method carries a large family of sauces.

• Beurre rouge. Red wine instead of white. Deeper, and it suits red meat and oily fish.
• Beurre nantais. The original, with shallot and a splash of cream for stability — most restaurant versions are this.
• Herb beurre blanc. Chervil, tarragon, chives or dill stirred in off the heat at the very end.
• Citrus. Replace some of the vinegar with lemon, lime or blood orange juice, reduced the same way.
• Saffron. Steeped in the reduction. Classic with white fish and mussels.
• Beurre rouge with a shallot and peppercorn reduction, which is most of the way to a bordelaise.
• Miso or soy in the reduction, which is not classical and works extremely well.
• A little cream in the reduction makes every one of these more forgiving, at a small cost in purity.

Common questions