Preparation

Bring vinegar and sugar to a boil in a 1-quart heavy nonreactive saucepan over moderate heat, stirring until sugar is dissolved. Reduce heat and simmer until slightly syrupy and reduced to about 1/2 cup, about 15 minutes. Pour into a heatproof bowl and cool completely.

Cooks' note: Syrup can be made 1 week ahead and kept in an airtight container at room temperature.