Preheat oven to 425°F. Whisk together flour, sugar, salt, and baking soda into a large mixing bowl.

Using your fingers, work the butter into the flour mixture until it resembles coarse meal, then add in the currants or raisins.

Make a well in the center of the flour mixture. Add beaten egg and buttermilk to well and mix in with a wooden spoon until dough is too stiff to stir.

Dust hands with a little flour, then gently knead dough in the bowl just long enough to form a rough ball. If the dough is too sticky to work with, add in a little more flour. Do not over-knead!

Transfer dough to a lightly floured surface and shape into a round loaf. Note that the dough will be a little sticky (a little like a shortcake biscuit dough). You want to work it just until the dough comes together. The bread will get tough if you knead it too much.

Transfer dough to a large, lightly greased cast-iron skillet or a baking sheet (it will flatten out a bit in the pan or on the baking sheet). Using a serrated knife, score top of dough about an inch and a half deep in an "X" shape. (The purpose of the scoring is to help heat get into the center of the dough while it cooks.)

Bake until bread is golden and bottom sounds hollow when tapped, about 35-45 minutes. (If you use a cast iron pan, it may take a little longer as it takes longer for the pan to heat up than a baking sheet.) Check for doneness by inserting a long, thin skewer into the center. If it comes out clean, it's done.

Remove pan or sheet from oven, let bread sit in the pan or on the sheet for 5-10 minutes, then remove to a rack to cool briefly. Serve bread warm, at room temperature, or sliced and toasted. Best when eaten warm and just baked.