Preheat oven to 350 degrees. Line cupcake pan with paper liners.
Beat the egg whites on high speed until soft peaks form about 2-3 minutes. Set aside.
Whisk together the flour, cornstarch, baking powder and salt.
Beat butter on high speed until smooth and creamy about one minute.
Add the sugar beating on high until the butter and sugar are creamed together. (3-4 minutes)
Beat on medium-high speed while adding in the egg yolk and vanilla.
Reducing the speed to low begin to add the dry ingredients, next add some of the milk. Alternate with the flour mixture and milk, mix after each addition, and ending with the addition of the flour mixture. Be careful to just blend the ingredients not over beat.
Using a spatula gently fold in the egg whites, chopped strawberries, and pink food coloring.
Using a medium ice cream scoop fill the batter into the lined cupcake tins.
Bake at 350 degrees for 20-24 minutes or until an inserted toothpick comes out clean.
Allow to cool in the cupcake pan for about 5 minutes before transferring cupcakes to a wire rack to cool completely.