Champagne Sauce - cooking recipe

Ingredients

1 cup veloute sauce (prev. posted-made with fish stock for fish or chicken stock for chicken)
1 cup champagne or 1 cup sparkling wine
1/2 cup sweet onions or 1/2 cup shallot, minced
1/2 cup butter, cut into pats
1 1/2 teaspoons fresh tarragon, chopped

Preparation

Place the onions and champagne into a sauce pan and bring it to a low boil and cook until it is reduced by half.
While the champagne and onions are cooking, heat but don't boil the veloute sauce.
Remove the champagne and onions from the heat and thoroughly stir in the veloute and the tarragon.
Lightly swirl the butter into the sauce and when the butter is very soft but not melted, spoon over fish or chicken (you want to have butter streaks on the sauce).