Beurre Blanc (Emulsified Butter Sauce — Reduction Base)

Ingredients

• 100 ml dry white wine (Muscadet or Sauvignon Blanc preferred)
• 30 ml white wine vinegar or Champagne vinegar
• 2 shallots, finely minced
• 1 thyme sprig
• 200 g cold unsalted butter, cut into 20 g cubes
• Salt and white pepper, to taste
• Optional: 5 ml fresh lemon juice

Method

1. 1
   Combine white wine, vinegar, shallots, and thyme in a heavy-bottomed saucepan over medium-high heat.
2. 2
   Reduce until approximately 30 ml of liquid remains and the shallots are just visible at the bottom (6–8 minutes); the reduction should be glossy and syrupy.
3. 3
   Remove from heat, discard thyme, and let cool to 50°C for 1 minute.
4. 4
   Return to very low heat and whisk in cold butter cube by cube, adding each piece only after the previous one is half-incorporated; never allow the sauce to exceed 55°C or the emulsion will break.
5. 5
   Once all butter is incorporated, pass through a fine-mesh sieve into a clean, warm pot.
6. 6
   Season with salt, white pepper, and lemon juice if desired.
7. 7
   Hold in a warm water bath at 43–50°C; stir gently every 2 minutes and never allow temperature to exceed 55°C.