Position a rack in the middle of the oven and preheat to 350 degrees F. Line two cupcake pans and set aside.

Mix dry ingredients together in a large bowl and set aside. In a medium bowl, mix wet ingredients together, including strawberries. Slowly stir wet ingredients in with the dry being careful not to over mix the batter. Pour batter into cupcake tins and bake in the oven for approximately 20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean. Allow cupcakes to cool in the pan and then remove to a baking rack to cool completely before frosting.

For frosting, combine egg whites, sugar, and salt in the heatproof bowl of a standing mixer set over a pan of simmering water. Whisk constantly by hand until mixture is warm to the touch and sugar has dissolved (the mixture should feel completely smooth when rubbed between your fingertips).

Attach the bowl to the mixer fitted with the whisk attachment. Starting on low and gradually increasing to medium-high speed, whisk until stiff peaks form. Continue mixing until the mixture is fluffy and glossy, and completely cool (test by touching the bottom of the bowl), about 10 minutes.

With mixer on medium-low speed, add the butter a few tablespoons at a time, mixing well after each addition. Once all butter has been added, whisk in vanilla. Switch to the paddle attachment, and continue beating on low speed until all air bubbles are eliminated, about 2 minutes. Scrape down sides of bowl with a flexible spatula, and continue beating until the frosting is completely smooth. Pipe or spread frosting onto cupcakes.