Place a rack into the center of the oven and preheat to 400 degrees F.
Prepare a baking sheet by lining it with parchment.
In a large mixing bowl, whisk together the flour, sugar, poppy seeds, baking powder, salt, and lemon zest.
Cut butter into smaller pieces and with a pastry cutter, cut butter into the flour mixture until it resembles coarse meal.
In a small mixing bowl, whisk together the egg and soured milk.
Pour the mixture into the dry ingredients and stir until it just comes together. Then using a rubber spatula, knead and fold it together about 8 to 10 times.
Prepare a flat surface by dusting it with flour, and turn the dough out onto it.
Divide the dough in half and pat each into a circle approximately 5 inches in diameter. Cut the dough into 6 wedges and transfer the entire disk of dough to the prepared baking sheet. Cutting it before baking allows for easy separation, but keeping the wedges together during baking allowed for the scones to be bit more moist than is typical.
Bake for 20 to 25 minutes or until tops are lightly golden and firm. Transfer to a wire rack and allow to cool for 10 minutes while you prepare the glaze.
In a medium microwavable bowl, whisk together the confectioners' sugar, lemon juice and butter.
Place bowl into the microwave and set on high for 45 seconds.
Whisk again to mix well, removing any lumps and allow to sit for a few minutes to cool.
Drizzle over scones and serve.