Preheat the oven to 400?F (204?C). Line muffin cups with paper liners (8 for big muffins, 10 for standard, or 22 for mini).

Lightly grease or spray the tops of the muffin tin with oil to prevent sticking.

Make lemon sugar by removing the zest from the lemon and rubbing it into the sugar until fragrant.

Whisk the flour, lemon sugar, baking powder, and salt in a large bowl.

In a measuring jug, add the oil, then crack in the egg. Pour in enough milk to reach the 1-cup line. Add vanilla extract and whisk until combined.

Add the wet ingredients to the dry ingredients. Stir gently until the batter comes together, being careful not to overmix.

Gently fold in the blueberries and about 2 tablespoons of fresh lemon juice.

Divide the batter between muffin cups, filling to the tops. Sprinkle a little sugar on top of each muffin.

Bake muffins for 15 to 20 minutes or until the tops are no longer wet and a toothpick comes out with crumbs.