Stir together milk and vinegar and allow to rest for 5 minutes.
Combine flour, oats, sugar, baking powder, salt, baking soda, and cinnamon in a blender and pulse several times.
Add milk mixture, oil, egg, and vanilla to blender and blend until smooth.
Use a 1/4 cup measuring cup to pour batter onto a greased griddle, skillet, or pan. Cook over medium heat (about 275 degrees) until edges look "dry" and bubbles form and pop in the batter. Flip over pancake and cook for another 45-60 seconds until browned on the second side. Repeat with remaining batter.
Serve pancakes immediately with your favorite toppings or freeze in airtight container and reheat in the microwave when ready to serve.