Preheat oven to 180°C (350°F). Place the flour, baking powder and sugar in a bowl. Place the oil, egg, milk and vanilla in a separate bowl and whisk to combine. Pour the liquid ingredients into the dry ingredients and mix until just combined. Add the blueberries and mix to combine. Spoon mixture into a 12-hole ½-cup capacity (125ml) muffin tin lined with paper patty cases. Sprinkle the tops with sugar and bake for 30–35 minutes or until cooked when tested with a skewer. Remove from tin and cool on a wire rack.