Pour off water from blender; dry well. Add 2 large egg yolks*, 1 Tbsp. fresh lemon juice, and 1 Tbsp. water and blend until mixture is smooth. With motor running, very gradually stream in melted butter, leaving milk solids at bottom of measuring glass behind. Blend until a smooth, creamy sauce forms.
04Pour sauce into a medium bowl. Stir in shallot reduction and 1 Tbsp. finely chopped tarragon. Taste and season with more salt, pepper, and/or lemon juice if needed.
Do Ahead: Sauce be made 1 hour ahead. Cover and let sit at room temperature.
*Raw egg is not recommended for infants, the elderly, people who are pregnant or have weakened immune systems...or folks who don’t like raw eggs.
Editor’s note: This recipe was originally published in March 2012. Head this way for some French desserts to serve for the final course →