Use this recipe as a sauce for Balsamic-Marinated Shrimp.
In a medium skillet over medium-high heat, saute shallot in oil until soft, about 3 minutes. Add garlic; cook until soft. Add salt, pepper, and cayenne; cook 1 minute. Add sugar and vinegars; cook 1 minute. Stir in tomatoes and rosemary; cook until slightly thickened, 5 minutes. Serve warm or at room temperature.