Set oven to 425F
Whisk the flours, salt, and soda together in a large mixing bowl. Make a well in the center, and add about 1 ½ cups of the buttermilk. Gradually mix the flour and buttermilk, adding the remaining buttermilk if your dough seems too dry. The dough will have a rough texture to it.
Transfer the dough to a floured surface and knead briefly until it comes together. Form into an 8 inch round disk. Transfer to a baking sheet and cut a cross in the top with a sharp knife.
Bake for about 25-30 minutes, or until golden brown. It should sound hollow when you rap the bottom.
Let cool for a few minutes, but then enjoy it while still warm, with some good Irish butter, of course!
