First, slice the strawberries and freeze them. (Do this a day in advance.)

Add the frozen strawberries and powdered sugar to a food processor. Blend on high speed for 10 seconds. Scrape down the sides with a spatula and blend again for another 5 seconds if needed. Add the paddle attachment, pour in the pasteurized egg whites (I used the kind sold in cartons), and mix on medium speed for 3 minutes.

Pour the mixture into a container and freeze for a few hours before serving.