1. In a medium bowl, combine flour, sugar, baking powder and salt. Grate butter into the flour mixture using large holes of a box grater. Using your fingers, work in the butter until the mixture resembles coarse crumbs. Add sour cream, orange juice and orange zest. Stir until combined.
2. Preheat oven to 350F (180C).
3. Place the dough (it will be sticky) on a lightly floured surface, flour your hands and pat it into a 7-inch circle about 3/4-inch thick. Use a pizza cutter (or a sharp knife) to cut the circle into 8 triangles.
4. Line a baking sheet with parchment paper. Place the scones on the prepared baking sheet, about 1 inch apart (you can use a knife to lift the scones).
5. Bake in the preheated oven until slightly golden, about 20 to 25 minutes. Cool for 10 minutes, meanwhile prepare the glaze.
6. In a small bowl, mix together powdered sugar, vanilla extract and the rest of the orange juice (the last ingredient). Whisk until smooth.
7. Drizzle the scones with the glaze.
8. Allow the glaze to harden and serve.