Combine the milk and vinegar in a small bowl. Set aside for at least 5 minutes to "sour".
Meanwhile, mix together the flour, sugar, baking powder and salt in a medium bowl. Set aside.
Once the milk has "soured", mix in the egg, oil and vanilla.
Mix the wet ingredients into the dry ingredients until fully incorporated. Add in the banana and mix well.
Heat a large skillet over medium heat and spray with cooking spray. Scoop 1/4 cup of batter for each pancake, and flip when bubbles are covering the surface of the pancake. Cook the other side until it is golden.