
Preheat oven to 350F (175C) and line a 12-count muffin tin with paper liners. Set aside.
In a large bowl, whisk together flour, sugar, cornstarch, baking powder, baking soda, and salt.
Use an electric mixer and slowly drizzle oil into mixture, mixing on low speed to combine. Mixture may appear crumbly, this is fine, but all of the dry ingredients should be moistened.
In a separate medium-sized mixing bowl or large measuring cup, whisk together buttermilk, lemon zest, lemon juice, eggs, and vanilla.
With mixer on low speed, slowly drizzle the wet mixture into the dry, stirring until completely combined.
Add blueberries and use a spatula to gently fold into the batter until well distributed.
Divide batter evenly into prepared muffin tin. Transfer to center rack of 350F (175C) preheated oven and bake for 20-22 minutes, until cupcakes are baked through and a toothpick inserted into the center of a cupcake comes out dry, or with a few moist crumbs.
Allow cupcakes to cool in their pan for 5 minutes before carefully removing to a cooling rack to finish cooling. Cool completely before frosting. I recommend my lemon frosting, blueberry frosting, or my new lemon cream cheese frosting.