Preheat oven to 350 degrees. Line a baking sheet with parchment paper. Measure the flour, sugar, baking powder, baking soda and salt into a bowl with high sides or the bowl of stand mixer and whisk to combine. Stir in the caraway seeds, orange zest and currants.

Dice the butter into 1/2 inch cubes. Use your hands or the paddle attachment of the stand mixer on low speed to blend the butter into dry ingredients until the texture becomes mealy. If you want to finish baking the soda bread the next day, cover the bowl with plastic wrap and chill overnight, otherwise proceed with the recipe.

Add 3/4 cup of the buttermilk at once, mixing just until the dough comes together, 30-35 seconds. Scrape the bottom and the sides to incorporate dry ingredients, then stir in enough buttermilk to bring the dough together. You may have buttermilk left over. Try not to over handle the dough. Just enough to incorporate the dry ingredients.

Turn the dough out onto a floured surface and divide it into 2 chunks. Gently shape the chunks into domed disks and score each one into quarters. (I made 2 elongated loaves with a single score down the middle.) Place on the prepared baking sheet and brush liberally with the egg wash (1 egg, 1 Tablespoons water, and pinch of salt whisked all together).

Bake for 30-35 minutes rotating the pan half way through the baking time. The soda bread should be shiny and golden brown. When cool sprinkle powdered sugar on top.