Combine sliced strawberries and the 2 tbsp. sugar. Cover and let sit in refrigerator at least 1 hour.
In a mixing bowl, stir together flour, 1 tbsp. sugar, baking powder, and baking soda. Using a pastry blender, cut in margarine or butter until mixture resembles coarse crumbs. Combine egg and buttermilk. Add to flour mixture all at once, stirring until combined.
Drop dough from a tablespoon onto an ungreased baking sheet, making 8 mounds.
Bake in a 450 degree oven for 7 - 8 minutes or until golden. Trasfer shortcakes to a wire rack and cool about 10 minutes.
Meanwhile, if using topping mix, prepare according to package directions using skim milk. To serve, cut shortcakes in half horizontally. Spoon half of the strawberries and one-fourth of the whipped topping over bottom layers. Replace tops. Spoon remaining strawberries and topping onto each shortcake (or spoon strawberries around shortcake). If desired, garnish with a strawberry fan.