1 quart fresh or frozen raspberries (about 1 pound)
1/2 cup sugar
1/4 black currant liqueur
1/2 cup water
Place all ingredients in a medium saucepan and bring to a simmer on medium heat. Simmer for 10 minutes, stirring occasionally. The berries will gradually disintegrate as they are cooking. Remove from heat and cool for 10 minutes.
Strain the sauce through a fine mesh wire sieve placed over a bowl, using the back of a spoon to push on the pulp. Throw away the seeds and pulp that remain in the sieve.
Allow the sauce to cool to room temperature. Pour the sauce into a clean jar with a lid and refrigerate until ready to serve.
This syrup can be stored for several days in the refrigerator.