Preheat the oven to 375℉. Line a baking sheet with parchment paper.
Mix together the flours, sugars, baking soda, baking powder and salt.
Use a hand, box or rotary grater to grate the butter into the dry ingredients. Use a fork or your fingers to quickly blend the mixture until it resembles bread crumbs. Alternately, you can use a pastry cutter, fork or two knives to work the butter into the dry ingredients.
Using a zester or a small holed grater, zest the lemon into a small bowl and set aside. The zest can also be removed using a vegetable peeler and then chopping the zest into small pieces.
Cut the lemon in half and juice it into a small measuring cup. Add bottled lemon juice, if necessary to make it equal ¼ cup + 2 tbsp (just over ⅓ cup).
In a separate bowl, whisk the egg, buttermilk, ¼ cup lemon juice and 1 tbsp lemon zest (reserve the rest of the juice and zest for the glaze). Add this mixture to the dry ingredients and stir swiftly with a fork until the mixture is evenly moist.
Turn the dough onto a floured surface and knead the mixture two or three times to make it come together. Sprinkle in a little flour if it’s too moist to shape.
Divide the dough into 2 equal portions and place them on the parchment-lined baking sheet. Shape each into a disk that is ½“ high and 6” in diameter. Cut each disk into 8 wedges and separate them slightly. They should be almost touching but not quite, which makes them easier to separate after cooking.
Bake for 22-25 minutes or until golden brown, flipping halfway through baking if the bottoms become too browned. Remove from baking sheet to a cooling rack.
While the scones are baking, mix together confectioners’ sugar, 2 tbsp lemon zest and the remaining lemon zest.
Allow the scones to cool for 15 minutes and drizzle with glaze. Scones can be served warm or at room temperature.
*If using freshly milled barley flour, make sure to weigh, not measure, the amount needed. This can be done before or after milling.
**If you don’t have buttermilk on hand, add ¼ cup buttermilk powder to the dry ingredients and ¾ cup regular milk or water to the wet ingredients.
Hack: Scones will remain fresh for 1-2 days at room temperature or up to a week in the refrigerator. They can also be tightly wrapped and frozen for up to 3 months.
Hack: To easily zest lemons or other citrus fruit, use a vegetable peeler. Lay unused zest in a single layer and freeze. Store, tightly wrapped, in the freezer for up to 6 months.
Hack: Leftover lemon juice can be frozen for up to 12 months. Pour lemon juice into an ice cube tray and place in the freezer until solid. Transfer to freezer bags or freezer-safe containers for storage.
Hack: Puree any leftover peeled lemons in the blender or food processor for use in recipes such as cakes, cookies or bread. 1 lemon yields about ½ cup, which can be sealed in a bag and stored in the freezer for up to 3 months.