Combine vinegar, shallots and tarragon in medium skillet; bring to a boil. Reduce heat to medium low and simmer until reduced to 1/3 cup.
Add 2 cups sherry and broth; bring to a boil. Reduce heat and simmer 25 to 30 minutes or until reduced to 1 cup.
Dissolve cornstarch in 1 tablespoon dry sherry. Add cornstarch mixture to skillet stirring constantly; cook and stir about 1 minute until sauce is slightly thickened. Whisk in mustard and honey. Remove from heat; whisk in butter. Serve warm.
Nutrition information per serving: 65.1 Calories; 4.5 Calories from fat; 0.5g Total Fat (0.3 g Saturated Fat; 0.1 g Monounsaturated Fat;) 1.8 mg Cholesterol; 291.6 mg Sodium; 4.8 g Total Carbohydrate; 0.1 g Dietary Fiber; 0.3 g Protein; 0.1 mg Iron; 0 mg NE Niacin; 0 mg Vitamin B6; 0 mcg Vitamin B12; 0 mg Zinc; 0.1 mcg Selenium; 0.4 mg Choline.