Preheat oven to 375 degrees F. Grease a baking sheet. Sift together flour, sugar, baking powder, soda, and salt in large mixing bowl. Using the tips of your fingers rub in butter until mixture resembles coarse meal. Stir in currants and caraway seeds. Combine egg and buttermilk and add to mixture. Blend until dry ingredients are well moistened. Turn dough onto floured board and knead for several minutes until smooth. Shape into a round ball and place on greased baking sheet. Press down on top of dough to flatten it slightly. Brush top and sides with blended egg and water. Using a sharp knife cut several slashes across the top/ Bake for 30 to 40 minutes or until a knife inserted in the center comes out clean.