Blueberry Ginger Sauce For Grilled Chicken

2 cups fresh blueberries (or frozen)
1/3 cup brown sugar, packed
1/4 cup very finely chopped sweet onion
1 small garlic clove, grated
1/4 cup golden raisins
3 Tbsp apple cider vinegar
1 1/2 tsp grated ginger root
1/4 tsp salt
1/4 tsp cinnamon
dash red pepper flakes
dash ground cloves

In a large heavy saucepan, add all ingredients, stirring to combine.
Bring to a boil and immediately turn heat to low.
Simmer, uncovered, slowly for 20 to 25 minutes or until sauce thickens and reduces.

Stir several times during cooking time.