Beurre Blanc

Name: Beurre Blanc
Prep time: 15 min
Total time: 15 min
Cuisine: France
Ingredients: 1 shallot, very finely chopped, about 30 g; 80 ml (⅓ cup) dry white wine, Muscadet or Sauvignon Blanc; 40 ml (2½ tbsp) white wine vinegar; 1 tbsp heavy cream, optional, for stability; 180 g (¾ cup / 1½ sticks) cold unsalted butter, cut in 2 cm cubes; 2 g (⅓ tsp) fine sea salt; 1 pinch white pepper; 1 tsp lemon juice, optional

The Loire Valley's butter sauce for fish

Makes: about 200 ml (¾ cup)
Hands-on: 15 min
Total: 15 min
Level: Some skill

Beurre blanc is a reduction of wine, vinegar and shallot into which cold butter is whisked until it becomes a pale, light, tangy sauce. It is the most elegant way to dress white fish, salmon or steamed vegetables.

Ingredients

1shallotvery finely chopped, about 30 g
80 mldry white wine (⅓ cup)Muscadet or Sauvignon Blanc
40 mlwhite wine vinegar (2½ tbsp)
1 tbspheavy creamoptional, for stability
180 gcold unsalted butter (¾ cup / 1½ sticks)cut in 2 cm cubes
2 gfine sea salt (⅓ tsp)
1 pinchwhite pepper
1 tsplemon juiceoptional

Diet: Vegetarian, Gluten-free
Allergens: milk, sulphites
Origin: France (Loire)

Method

Put the shallot, wine and vinegar in a small, heavy saucepan. Simmer over medium heat until only about 2 tablespoons of syrupy liquid remain, 6–8 minutes.
Add the cream, if using, and bubble for 30 seconds.
Turn the heat to low. Add 2–3 cubes of butter and whisk constantly until almost melted, then add more, a couple of cubes at a time. The sauce should never bubble; lift the pan off the heat if it gets too hot.
Continue until all the butter is in and the sauce is pale, creamy and coats a spoon, about 5 minutes. It should feel warm, not hot, around 50–55°C (120–130°F).
Season with salt, white pepper and lemon. Strain out the shallots if you want a smooth sauce, or leave them in for texture.
Serve immediately, or keep in a warm (not hot) place for up to 30 minutes.

Why it works

Butter is already an emulsion of fat, water and milk solids. Whisking it in a little at a time into a hot, acidic reduction keeps it in that emulsified state as it melts, rather than separating into clear fat. The milk proteins act as the emulsifier; a spoonful of cream adds more of them, making the sauce harder to break. Much above 60°C (140°F) the emulsion starts to break; below about 30°C (86°F) the butter begins to set.

Common mistakes

Too much heat: the sauce turns oily. Keep it barely warm and whisk constantly.
Adding butter in big lumps: the sauce cools and won't emulsify. Small cubes, steady pace.
Reheating: it cannot be reheated once cold. Make it just before serving.