Every day at the resort at 1:00 pm, we (the staff) would charge to the dining room to get last call for lunch. This, of course was breakfast for the band. We would stuff ourselves and invariably end the meal with an order of blueberries and sour cream, which would push it over the top.
In a medium saucepan, boil 1/2 cup of the port wine and the sugar for 3 minutes to cook off some of the alcohol.
In the meantime, in a small bowl, whisk together the remaining 1/4 cup port, vanilla, and cornstarch. Add it to the pot and cook until clear, about 3 more minutes. Add 1 pint of the blueberries and continue to cook until the sauce thickens and the blueberries soften. Let cool and add the other blueberries. Serve with a healthy dollop of sour cream.