Dijon-cream sauce

Bring beef broth and whipping cream to a boil in a saucepan. Boil gently until reduced about 2/3; sauce will be thick enough to coat a spoon. To thicken sauce more, in a small dish, mix the arrowroot with the same amount of water. Add to sauce and stir until thickened. Remove from heat; stir butter, a little at a time, until all the butter is melted. Stir in mustard and vinegar, adjusting amounts to taste. Sprinkle with peppercorns and mustard seeds. Makes about 1 cup if scaled at 6 servings.