• In small saucepan, stir egg yolks and lemon juice briskly with wooden spoon. Add half the butter; stir over very low heat until butter is melted.
  
• Add remaining butter, stirring briskly until butter is melted and sauce thickens. (Be sure butter melts slowly as this gives eggs time to cook and thicken the sauce without curdling). Serve warm or at room temperature.

Béarnaise Sauce

• Stir in the minced onion, the tarragon leaves,the chervil leaves (if using) and the white wine or, if you prefer, the white wine vinegar into the Hollandaise Sauce.
  

Note

• Makes one cup.  Leftover sauce can be stored covered in the refrigerator for several days.  Before serving, stir in small amount of hot water or heat briefly in the microwave and stir well.