• Steps 1
• 5 Mins

Melt the butter in a saucepan and then set it aside to cool. The butter should be between 40-50 degrees Celsius when used, not hotter! While the butter is melting, peel and finely chop the shallot.

Butter Shallot Tarragon

• Steps 2
• 10 Mins

Mix the finely chopped onion, vinegar, water, crushed white peppercorns, and about half of the tarragon in a heavy-bottomed saucepan and bring to a boil. Reduce to about half of the volume. Then strain the mixture and return it to the saucepan. Separate the egg yolks from the egg whites while the mixture is reducing.

Shallot Vinegar, white wine Water White pepper Tarragon Yolk

• Steps 3
• 6 Mins

Here's a crucial step, and it's important to keep the temperature low, no more than about 50 degrees Celsius. If it gets too hot, the egg yolk will coagulate and become grainy, causing the sauce to curdle. Do this: First, pour the vinegar and tarragon reduction back into the pan and gently warm it to about 40 degrees Celsius. Add the egg yolks and whisk until fluffy. Then slowly drizzle in the butter a few drops at a time, vigorously whisking so the butter binds with the egg yolk while the pan is gently heated. When the mixture begins to thicken slightly, remove the pan from the heat and place it, for example, on a damp cloth to prevent slipping. Continue to add the rest of the butter while whisking vigorously until it reaches the right consistency, similar to mayonnaise. For a thinner sauce, try gently warming it to about 50 degrees Celsius while whisking. If the sauce curdles, cool it quickly, either with an ice cube, a tablespoon of cold water, or by placing the pan in a cold water bath while vigorously whisking.

Yolk Butter

• Steps 4
• 3 Mins

When the sauce reaches the desired consistency, add the rest of the finely chopped tarragon and parsley. Stir and season with salt. Pour into a bowl—importantly, ensure the sauce is not heated above 55-60 degrees Celsius on a residual heat, as it will curdle immediately.

Tarragon Parsley Salt

• Steps 5
• 2 Mins

Ready to serve!