Some similar recipes call for adding all ingredients to the blender, skipping the simmering step. Simmering the berries does a few beneficial things: Softens the berries making it easier to extract more of the delicious juice Sweetens the berries and their juice by allowing them to cool with the sugar added Deepens the flavor of the vinaigrette by taking a few extra minutes for this step Also passing the berries through the sieve removes the pesky seeds. Adding everything to the blender will incorporate the seeds into the dressing….and your teeth.