Adjust oven rack to lower-middle position and preheat oven to 400 degrees. Line a baking sheet with parchment paper.
In a medium bowl, combine sugar and orange zest; mix with your fingertips until the sugar is moistened and fragrant. Add in the flour, baking powder, baking soda and salt and mix until combined.
Grate butter into flour mixture on the large holes of a box grater; use your fingers to work in the butter until the mixture resembles coarse meal.
In a small bowl, whisk the sour cream and egg until smooth.
Using a fork, stir sour cream mixture into flour mixture until large dough clumps form. Use your hands to press the dough against the bowl into a ball. The dough will be sticky first, but as you press, the dough will come together.
Place on a lightly floured surface and pat into a 7-inch circle about 3/4-inch thick. Use a sharp knife to cut into 8 triangles; place on prepared baking sheet, about 1 inch apart. Bake until golden, about 15 to 17 minutes. Cool for 10 minutes and prepare the glaze.
In a medium bowl, prepare the glaze by mixing together the melted butter, confectioners’ sugar, vanilla and orange juice. Whisk until smooth. Dip the top of the scones into the glaze and allow the glaze to harden. At this point, you can leave them as is or go for the double dip. I glazed twice.