Preheat the oven to 350 degrees F. Line 2 (24-count) mini muffin tins with paper liners.
In a blender combine the strawberries (reserve about 12 small strawberries for garnish, slicing each into 4) with 1/4 cup water and puree until smooth. Puree should equal about 1 3/4 cups, if not add more water. Set aside 1/4 cup of the puree for frosting.
In a large mixing bowl, using an electric mixer, beat together the cake mix, egg whites, vegetable oil, and 1 1/2 cups of pureed strawberries for 2 minutes. Scrape down the sides of bowl to make sure all the batter is well incorporated. Using a mini ice-cream scoop, fill the muffin tins about 3/4 of the way to the top. Bake until the tops are golden and a toothpick inserted in the center comes out clean, about 8 to 10 minutes. Remove the tins from the oven cool slightly before removing the muffins. Cool completely on a wire rack before frosting.
Frosting: In a mixing bowl that fits over the top of a pot of boiling water, combine all of the ingredients, except the vanilla and food coloring. Beat with hand mixer on medium speed, while mixture cooks, until peaks are formed when the beaters are lifted out of the bowl, about 7 minutes. Remove the bowl from the heat and add vanilla and red food coloring to the desired pink shade. Frost the cupcakes with the colored frosting and garnish each with a strawberry slice.