Preheat oven to 350°F. Line a muffin pan with cupcake liners or grease well.
Sift together the flour and cornstarch. Add the baking soda, cocoa powder, and salt together and whisk to combine. Set aside.
With a mixer fitted with a whisk attachment, beat 2 egg whites on high speed in until soft peaks form, about 2-3 minutes. Set aside.
With a mixer fitted with a paddle attachment, beat the butter on high speed until it is smooth and creamy, about 1 minute. Add the sugar to the butter and cream together on high speed for 2 minutes. Scrape down the sides of the bowl and beat again. With the mixer on low speed, slowly add the oil and then beat on high speed for 2 minutes.
Add the 2 egg yolks and the vanilla. Beat on medium-high speed until well combined. Scrape down the bowl and mix again. Add the vinegar and the food coloring until you reach your desired color.
With the mixer on low speed, add the dry ingredients in three additions alternating with the buttermilk, beginning and ending with the dry ingredients. Mix after each addition just until incorporated. Be careful to not overmix the batter.
Fold the whipped egg whites into the batter with a rubber spatula. Fold in carefully but completely.
Scoop the batter into the cupcake liners, filling ⅔ of the way full. Bake for 18-22 minutes or until the tops of the cupcakes spring back when gently touched and a toothpick inserted in the center comes out clean. Allow to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Cool the cupcakes completely before icing them with your chosen frosting. Cream cheese frosting is the traditional icing for Red Velvet but can be too thin to pipe.