Heat the oven to 350°F. Prepare a muffin pan with liners or grease well.

Sift together flour, cornstarch, baking soda, cocoa powder, and salt. Set aside.

Using a mixer with a whisk attachment, beat 2 egg whites until soft peaks form (about 2-3 mins). Set aside.

Switch to a paddle attachment, beat butter until smooth. Add sugar, creaming on high for 2 mins. Scrape down, add oil, and beat for another 2 mins.

Incorporate 2 egg yolks and vanilla. Mix well, scrape down, and add vinegar and food coloring for desired hue.

On low speed, add dry ingredients in three parts, alternating with buttermilk. Begin and end with dry ingredients. Mix after each addition, avoiding overmixing.

Gently fold whipped egg whites into the batter.

Fill cupcake liners 2/3 full and bake for 18-22 minutes until tops spring back. Cool for 5 minutes, then transfer to a wire rack.

Ensure cupcakes are completely cool before frosting with your chosen icing. Cream cheese frosting is a classic choice, though it may be too thin for piping.