Piquant Herb Sauce - cooking recipe

Ingredients

1/2 cup dry white wine
1/4 cup white wine vinegar
1/2 cup chopped fresh parsley
1 small onion, quartered
2 cloves garlic
3 teaspoons dried tarragon, lightly crushed
1/2 teaspoon dried chervil, lightly crushed
1/4 teaspoon white pepper
1 cup mayonnaise (Best Foods or Hellman's)
1 egg yolk (preferred) (optional)

Preparation

Mix first 8 ingredients in blender at high speed until smooth.
In small saucepan, stir over medium heat until reduced to 1/3 cup.
Strain and return liquid to pan.
Stir in mayonnaise and heat until warm.
If too thin, beat 3 Tbsp of sauce thoroughly with egg yolk, and add yolk to remainder of sauce (I always add yolk!).
Continue to heat, stirring constantly.
DO NOT BOIL!
Garnish with chopped parsley if desired.
Serve with beef or chicken.
Outstanding substitute for Bearnaise Sauce, very easy to make and almost foolproof.