1. Sprinkle gelatin over water in custard cup. Place in pan of hot water, heat until dissolved.
2. Puree strawberries with punch in blender.
3. Stir in yogurt, sour cream, and dissolved gelatin. Refrigerate until partially set.
4. Beat egg whites with sugar until stiff. Fold into yogurt mixture. Turn into serving bowl or 8 individual dishes. Freeze or refrigerate until set.