Step 1 Place the frozen berries and sugar in a medium saucepan on the stove top (the heat from the pilot should be enough to warm the berries) and let them thaw and macerate for at least 30 minutes, maybe more.
Step 2 When the berries are completely thawed, press the berries through a strainer into a bowl, saving the puree and juice to make the sauce (discard the seeds and solids).
Step 3Stir in the lemon juice, cover and refrigerate until needed. The sauce will keep refrigerated for 1 week.