I have a rule that I don't like to mix more than two leftover fruits or the flavors get muddled. Pears and apples are a great combo. Blackberries and blueberries are another one. I simply love to take fruit that's slightly past its prime and simmer it with some jam or honey until the fruit becomes soft and the flavors meld. Then it's time to break out the toast!
In a medium skillet over medium heat, simmer the blueberries, jam, red wine vinegar and water until the liquid reduces and thickens.
Stir and mash some of the fruit with the back of a spoon and continue to cook 8–10 minutes or until the fruit is tender.
Cool for 15–20 minutes. Spread on toast. Devour.