Preheat your oven to 375°F (190°C). Line your muffin tin.
Whisk the flour, sugar, baking powder, and salt in a bowl.
In a different bowl, mix the oil, egg, vanilla, milk, lemon zest, and juice.
Pour the wet mix into the dry mix. Fold it together gently. Do not overmix.
Add the blueberries. Fold them in carefully so they do not break.
Fill each muffin cup about 2/3 full.
Bake for 18 to 20 minutes. Use a toothpick to check if they are done.