Chop the shallots and fry them with the blueberries in the vegetable oil in a pan.
Add the wine, water and beef stock, and let it simmer for 15 minutes.
Pour the sauce through a sieve, use a large spoon to press all the liquid through the sieve. Pour the sauce back into the pan, heat it up and add the corn starch.
Bring it to boil, then remove from the stove. Add salt and pepper to taste. When serving, sprinkle a few blueberries on top of the sauce.