Preheat oven to 400F. Prepare a baking sheet with parchment paper. In a small bowl, whisk together sour cream, lemon juice, zest and egg.
In a large bowl, whisk together flours, sugar, baking powder, baking soda and salt. Using a silicone spatula, fold in grated butter and sour cream mixture; stir until it’s almost fully combined. Toss in crystallized ginger and milk and stir just until everything is fully moistened—use your hands to help you bring it all together.
Lightly flour your countertop. Turn dough out onto worksurface and use your hands to form into an 8” circle about 1” high. Cut dough into 8 equal triangles and place on prepared baking sheet. Brush the scones with beaten egg and sprinkle with sugar. If you have the time, chill sheet pan about 20 minutes before baking—this will help the scones keep their shape.
Bake about 18 minutes, until golden brown and puffy. Cool scones on a wire rack.
In a small bowl, add powdered sugar and lemon zest. Slowly whisk in orange juice, 1 tablespoon at a time, until a thick but pourable consistency is reached. When scones have cooled, use a spoon to drizzle each with glaze and serve.