Preheat the oven to 350 degrees. Spray a baking pan (8X8 or similar size. If using a different size, please be aware baking times may vary) generously with cooking spray.
Combine the vinegar and milk in a small bowl. Set aside, and allow to "sour" for a few minutes.
Combine Greek yogurt and sugar until evenly mixed. Add in the egg and vanilla and mix until combined.
Combine blueberries with 20 g of flour. Coat blueberries with flour and then set aside.
To the wet ingredients, add 105 g of flour (half), baking powder, and salt. Stir until completely combined, but do not over mix. Then add milk and vinegar mixture and remaining flour (105 g). Stir until completely combined, but do not over mix. Fold in blueberries, but do not add any remaining flour that was not coating the blueberries.
Pour batter into prepared pan. Sprinkle evenly with remaining 10 g of sugar and bake for 40-50 minutes, or until the edges begin to brown and a toothpick inserted into the center comes out mostly clean with a few moist crumbs. Begin checking with a toothpick around the 40 minute mark.
Allow to cool for 15 minutes, slice into 9 squares, and serve.