Preheat your oven to 400°F (200°C).
Line a baking sheet with parchment paper or a silicone baking mat for easy cleanup.
In a large mixing bowl, combine the flour, granulated sugar, baking powder, baking soda, and salt.
Add in the cold, cubed butter and mix until the mixture resembles coarse crumbs.
In another bowl, whisk together sour cream, egg, lemon zest, and lemon juice.
Add the wet ingredients to the dry ingredients and stir until just combined.
Transfer the dough to a lightly floured surface and knead gently until it comes together.
Pat the dough into a circle about 1 inch thick, and use a knife to divide into 8 wedges.
Bake for 15-20 minutes or until golden brown.
Cool on a wire rack and drizzle with a glaze made from lemon juice and powdered sugar.