Preheat oven to 350F. Prepare a baking sheet with parchment paper or a silicone mat. Set aside.
In a large measuring cup combine milk and lemon juice to make homemade buttermilk if needed. Set aside
In a large bowl, combine the flour, salt, sugar, baking powder, baking soda, and lemon zest. Stir to combine.
Add the butter pieces and use your hands or a pastry blender to break the butter down into small pieces. I like to use my hands and smash each cube until the pieces are pea-sized. Fold in the raspberries.
Add the egg yolk to the buttermilk mixture and stir with a fork to combine. Pour wet ingredients into the dry ingredients and use a spatula to stir until a shaggy dough forms.
Turn dough onto a lightly floured surface and knead gently until the dough feels cohesive without large floury- spots.
Shape dough into a 6-8 inch disk and cut into wedges.
Brush with egg white and bake for 15-20 minutes, or until the edges are golden brown.
Allow scones to cool slightly on a wire rack while you make the glaze, combining the powdered sugar and lemon juice until a smooth glaze forms.
Drizzle the glaze onto the scones and enjoy. Scones are best the day you bake them buy can last in an airtight container for up to 3 days.