This tart, velvety, intensely flavored sauce is the essence of fresh raspberries. The secret is that the juice is concentrated to a quarter of its original volume but the pulp is not cooked at all.
In a strainer suspended over a deep bowl, thaw the raspberries completely. This will take several hours. (To speed thawing, place in an oven with a pilot light.) Press the berries to force out all the juice. There should be
In a small saucepan, boil the juice until it is reduced to