Preheat oven to 375 degrees. Prepare a baking sheet with parchment paper or a silicone baking mat. Set aside.
Add flour, sugar, poppyseeds, lemon peel, and salt to a large bowl and whisk together to combine. Cube the butter and add to the flour mixture. Using your hands, cut the butter into the flour until the butter is the size of large crumbs.
In a small bowl, whisk egg and lemon juice together. Make a well in the flour-butter mixture. Add egg and buttermilk. Fold the flour-butter mixture into the center to mix in the liquid ingredients. Gently mix together until ball forms.
Turn ball of dough onto floured surface. Using a rolling pin, roll dough into an 8-inch round. Cut round into 8 wedges, similar to slicing a pizza.
Transfer wedges to prepared baking sheet, leaving about 2 inches in-between each scone. Bake in preheated oven until toothpick comes out clean when inserted, about 20-22 minutes.
Remove scones from oven and let cool. Once completely cooled, dip tops of scones into icing and let the icing harden before serving.