1. Add butter, rosemary, and onion to a large saute pan. Saute over moderate heat,
stirring as needed until the onion is softened and lightly browned (about 10 minutes).
2. Add 1/2 of the white cooking wine and bring to a boil for about 3 minutes until the
wine is almost evaporated.
3. Add the chicken stock, bay leaf an peppercorns and boil about 30 minutes, reducing
the liquid to 1 1/2 cups.
4. In a separate saucepan combine the balsamic vinegar, shallots, and the remaining
white cooking wine. Boil gently until the liquid is reduced to 1/4 cup (about 8
5. Add the reduced chicken broth and cook for 2 minutes, stirring occasionally.
6. Strain the sauce into a small saucepan for immediate use or into a bowl for