Beurre Blanc

Beurre blanc ("white butter") is a classic French sauce from the Loire Valley made by whisking cold butter, piece by piece, into a sharp reduction of white wine, vinegar and shallots. The result is a pale, creamy, tangy sauce that's actually a warm emulsion of butterfat in a tiny amount of water.

How it works

Butter is already an emulsion: roughly 80–82% fat, 16–18% water and about 1% milk solids. When you melt butter quickly, it separates into clear fat and milky liquid. When you whisk cold butter slowly into a hot reduction, it melts gradually, and its own milk proteins and phospholipids coat the fat droplets, keeping them suspended in the reduction.

That's why beurre blanc works without egg yolk, but it's fragile:

• Too hot (above about 60 °C / 140 °F): proteins can't hold the fat; the sauce turns greasy and thin.
• Too cold (below about 30 °C / 86 °F): butterfat starts to solidify; the sauce stiffens and breaks when reheated carelessly.
• Just right: 50–60 °C / 120–140 °F, warm to the touch but not hot.

Basic proportions

• 60 ml (¼ cup) dry white wine
• 60 ml (¼ cup) white wine vinegar or lemon juice
• 1 small shallot (about 30 g), finely minced
• 170–225 g (¾–1 cup) cold unsalted butter, cubed
• Salt and white pepper to taste

Simmer wine, vinegar and shallot until only about 2 tbsp (30 ml) of liquid remains. Lower the heat, then whisk in butter a few cubes at a time, adding more as each piece is nearly melted. Strain out the shallots if you want a silky sauce.

Stabilizing tricks

• Add cream: whisking 2 tbsp (30 ml) heavy cream into the reduction before the butter adds extra proteins and makes the sauce far more forgiving.
• Keep butter cold, so it melts slowly and emulsifies.
• Work off and on the heat, lifting the pan whenever the edges start to bubble.

Variations

• Beurre rouge: red wine instead of white.
• Citrus beurre blanc: orange or yuzu juice in the reduction.
• Herb beurre blanc: chives, tarragon or dill stirred in at the end.

Common mistakes

• Reducing too little, leaving a thin, acidic sauce.
• Adding the butter too quickly or all at once.
• Letting the sauce boil after the butter goes in.
• Holding it on direct heat while you finish the rest of dinner.