Start by making your roasted strawberry puree. Pre-heat your oven to 375 degrees. Toss the strawberries with the sugar in a shallow baking dish, and roast for 25 minutes until the berries are soft, slightly darkened, and juicy. Cool for about 10 minutes, then transfer the berries and juices to a blender or food processor and puree until smooth. Strain the puree through a fine mesh strainer into a mason jar or airtight container. Refrigerate until completely chilled.