Preheat the oven to 375 degrees F. Line a large baking sheet with parchment paper.
Place the buttermilk, sour cream, egg and zest in a bowl and whisk to combine. Place the flour, granulated sugar, baking powder, baking soda and salt in a second bowl and whisk to combine. With a pastry cutter, 2 forks or your fingers tips, cut the butter into the flour mixture until it’s thoroughly blended in.
Gently stir the wet ingredients into the dry until a moist, loose dough forms. Turn the dough onto a floured surface and gently knead until it just holds together. Form the dough into a circle that's 1" thick. With a floured, 2" round cookie cutter, cut the dough into rounds and place on the baking sheet. Knead and press the trimmings of dough back together and cut it into rounds.
Bake the shortcakes in the middle of the oven 18 to 20 minutes, or until puffed and light golden. Cool the shortcakes to room temperature.
Whip the whipping cream until soft peaks form. Sweeten to taste with icing sugar and beat until stiff peaks form. Cut the shortcakes in half horizontally and set the bottom halves on a serving platter. Top the bottom halves with whipped cream and strawberries. Replace the top halves of the shortcakes. Dust with icing sugar and serve.