Put all of the ingredients in a heavy-duty 3-quart saucepan and bring to a boil. Turn the heat down to medium, cover, and simmer, stirring occasionally, until the plumbs break down, about 10 minutes. Uncover and simmer until thick, 5 to 7 minutes
Puree the sauce in a blender until smooth. Use or cool to room temperature and refrigerate in an airtight container for up to 1 week.