In a medium bowl stir together strawberries and the 2 tablespoons sugar. Cover and chill for at least 1 hour.
In another medium bowl stir together flour, the 1 tablespoon sugar, the baking powder, and baking soda. Using a pastry blender, cut in butter until the mixture resembles coarse crumbs. Combine egg and buttermilk; add to flour mixture all at once. Stir just until moistened. Drop the dough from a tablespoon into 8 mounds on an ungreased baking sheet.
Bake in a 450 degree F oven for 7 to 8 minutes or until golden. Transfer the shortcakes to a wire rack; cool about 10 minutes. Meanwhile, if using topping mix, prepare according to package directions using fat-free milk.
To serve, cut shortcakes in half horizontally. Place bottom halves on plates. Top with strawberries and whipped topping. Replace top halves of shortcakes. Makes 8 servings.