Preheat the waffle maker.
In a mixing bowl whisk together flour, cornstarch, baking powder, baking soda, and salt and set aside.
Get a separate mixing bowl and whisk together milk, vegetable oil, vanilla extract, and egg yolks until combined.
In the bowl of a stand mixer whisk the egg white on high until soft peaks form.
Add the sugar and whip until stiff peaks form.
While whisking, pour milk mixture into well in flour mixture and mix just until combined.
Fold in egg white mixture, the mixture will be lumpy.
Add in the blueberries and gently mix.
Cook batter in waffle iron for 4-6 minutes (depends on the heat and brand of your waffle maker) using roughly 1/2 cup of batter per waffle.