2 cups all-purpose unbleached flour
1/3 cup + 1 Tbsp sugar
1 tsp baking powder
1/4 tsp baking soda
1/2 tsp kosher salt
1/2 tsp ground cardamom
8 Tbsp (1 stick) unsalted butter, frozen
1/2 cup currants (or golden raisins)
1/2 cup sour cream
1 large egg
Preheat oven to 400°F.
In a large bowl, combine flour, 1/3 cup sugar, baking powder, baking soda, salt and cardamom. Set a box grater into the flour mixture, and on the largest holes, grate the butter right into the flour; the end will be hard to hold on to, so just use your fingers or a knife to break it up (hint: if you dip the butter into the flour as it gets slippery to handle, it will be easier to grate).
Using your fingertips, combine the butter and flour mixture until the texture resembles a coarse cornmeal. Then, stir in the currants.
In a small bowl, whisk together the sour cream and egg, until smooth. Using a fork, stir the sour cream mixture into the flour. When clumps start to form, use your hands to bring the dough together by pushing up against the side of the bowl. It will seem like there isn't enough liquid to moisten the dough, but as you keep pushing, it will come together. As soon as it just holds its shape, remove the dough to a lightly floured counter top.
Press or roll the dough into a circle approximately 7-8 inches in diameter, and 3/4 inch thick. Using a very sharp knife, cut the dough into 8 wedges.
Place the wedges on a rimmed baking sheet lined with a Silpat (silicone mat) or parchment paper. Make sure they are at least one inch apart. Sprinkle the remaining 1 Tbsp sugar over the scones, and place the baking sheet on the middle rack of the oven. Bake for 16 minutes, or until lightly golden brown.
Cool for a few minutes, and serve warm or at room temperature.