Heat oven to 400 degrees F. Then, line 8 standard-size muffin cups with paper liners. Add 1 to 2 tablespoons of water to the 4 empty muffin cups (this helps to make sure the muffins bake evenly).
Combine flour, 3/4 cup of the sugar, baking powder and the salt in a large bowl with a whisk. Whisk at least 10 times to make sure the baking powder and salt have evenly dispersed.
Next, add vegetable oil to a measuring jug that holds at least 1 cup. Add the egg then fill the jug to the 1-cup line with milk (this should be 1/3 to a 1/2 cup of milk). Add vanilla extract and whisk until combined.
Add milk mixture to the bowl with flour and sugar then use a fork to combine. Do not over mix. (The muffin batter should be thick and scoopable, but not dry like dough). Add blueberries and use a spatula or spoon to gently fold the blueberries into the muffin batter.
Divide batter between 8 muffin cups. (The batter will come to the tops of the paper liners). Then, sprinkle a little sugar on top of each muffin.
Bake blueberry muffins 15 to 20 minutes or until tops are no longer wet and a toothpick inserted into the middle of a muffin comes out with crumbs, not wet batter. Transfer muffins to a cooling rack and cool completely.