Bring juice to a boil in a large saucepan or skillet over high heat. Cook until reduced to about 2/3 cup, about 10 minutes.Advertisement
Stir together kirsch (or orange liqueur) and cornstarch in a small bowl; whisk into the sauce and cook until it has thickened and become clear again. Remove the pan from the heat and stir in raspberries; let stand briefly until the berries have thawed. Serve warm or cool.