1Preheat the oven to 375 degrees F. Line a sheet pan with parchment paper.
2Combine the flour, sugar, baking soda and salt into a bowl of an electric mixer fitted with a paddle attachment. Add the butter and mix on low speed until the butter is mixed into the flour.
3With a fork, lightly beat the buttermilk, egg and orange zest together in a measuring cup. With the mixer on low speed, slowly add the buttermilk mixture into the flour mixture. Combine the currants with 1 tablespoon of flour and mix into the dough. It will be very wet.
4Dump the dough onto a well-floured board and knead it a few times into a round loaf. Place the loaf on the prepared sheet pan and lightly cut an X into the top of the bread with a serrated knife. Bake for 45-55 minutes, or until a cake tester comes out clean. When you tap the loaf, it will have a hollow sound.
5Cool on a baking rack. Serve warm or at room temperature.