Combine the flour, sugar, salt, baking soda, baking powder, and butter in the bowl of an electric mixer. Using the paddle attachment, mix at low speed until the butter is the size of small peas. Add the oats, currants, and chopped orange zest. Continue to mix, slowly pouring in the buttermilk, just until the dough comes together.
Put the dough on a lightly floured board and roll it out into a