In a large glass or metal mixing bowl, beat egg whites until foamy. Gradually add white sugar and vanilla, continuing to beat until soft peaks form. Carefully fold in sour cream until well blended. Fold in any additional flavorings or goodies at this time.

Place mixture into the freezer and stir every 30 minutes or so until frozen. This can be made without stirring, but the texture will be icy rather than creamy. If you have an ice cream maker, you can put the ice cream mixture in the maker and follow the manufacturer’s instructions.