Preheat a nonstick griddle to 375 degrees F.
In a large glass bowl, combine the milk and vinegar and let the mixture curdle while you mix together the other ingredients.
In a separate large bowl, whisk to combine the whole wheat flour, baking powder, baking soda, salt, and cinnamon. Set aside.
To the curdled milk, add eggs, melted butter, and vanilla. Whisk to combine. Pour this wet mixture into the dry ingredients, and stir the two together until just barely mixed. Do not over mix.
Add small scoops of pancake batter (approximately ¼ cup per scoop) to the griddle. Cook for a few minutes, until bubbles form on the surface. Flip the pancakes with a turner and cook for a few minutes on the other side, until the bottom is golden brown.
While cooking pancakes, begin preparing the fruit sauce by combining the fruit and juice in a small saucepan and bring to medium-high heat.
Once bubbling, reduce to medium-low heat and use a wooden spoon to mash the fruit. Add cinnamon if preferred. Continue cooking for about 10 minutes, occasionally mashing fruit to combine.
Remove from heat and serve warm over pancakes (no syrup needed!). The sauce is also delicious on French toast, ice cream, or stirred into oatmeal or yogurt. Store any extra sauce in the refrigerator.