Preheat your oven to 400°F and line a 12-cup muffin tin with paper liners.
Whisk together flour, sugar, baking powder, and salt in a large bowl.
In a measuring cup, combine oil, egg, milk, and vanilla.
Add wet ingredients to dry ingredients and stir just until combined (don't overmix!).
Gently fold in blueberries.
Fill muffin cups about ¾ full with batter.
Bake for 17-20 minutes until a toothpick comes out clean.