1. Position a rack in the middle of the oven and preheat oven to 400 °F.
2. Combine all dry ingredients except the butter and shortening in a large mixing bowl. Use a fork to mix well. Be sure the zest is well-distributed and not clumped together.
3. Cut the butter and shortening into small (1/8") cubes and toss in the dry mix to coat. Move the entire mixing bowl to the freezer for 10 minutes.
4. Meanwhile, mix all wet ingredients well and place in refrigerator to stay cool.
5. Remove the dry ingredients from the freezer and use the fork to cut the fat into the flour mixture. Return the mixing bowl to the freezer for another 5 minutes.
6. Remove the dry ingredients from the freezer and form a well in the center. Remove the wet ingredients from the refrigerator and pour into the well. Use a pastry scraper to fold the dry mix over top of the well, incorporating the wet into the dry. Do not overmix: when the mixture begins to form clumps, return the mixing bowl (with the pastry scraper in it) to the freezer for 5 minutes.
7. Cut a sheet of parchment to fit a cookie sheet. Remove the mixing bowl from the freezer and use the pastry scraper to fold the dough from one edge of the bowl to the other, pressing gently. Do this about 8 times, then move the dough onto the parchment sheet.
8. Use the parchment (or another piece) to gently form the dough into a disc. If the dough becomes sticky, dust with flour. Cut the disc into 8 wedges and separate from each other.
9. Brush each wedge with water (or egg wash) and sprinkle with coarse sugar. Bake at 400 °F for 10 to 15 minutes or until the surface is golden and beginning to brown at the edges.
10. Remove from the oven and slide the scones on the parchment onto a cooling rack.

I particularly like eating these slightly warm, with vanilla cinnamon bun icing melted over them. A cream cheese icing might be nice, too.