Heat oven to 400°F. In medium bowl, combine flour, 1/4 cup sugar, baking powder, cardamom and salt; mix well. With pastry blender or fork, cut in margarine until mixture is crumbly. Stir in currants and orange peel.
In small bowl, combine buttermilk and egg; blend well. Add all at once; stir just until dry ingredients are moistened.
On well-floured surface, gently knead dough 5 or 6 times. Place on ungreased cookie sheet; press into 8-inch round, about 1 inch thick. Cut into 8 wedges; do not separate. Sprinkle with 1 teaspoon sugar.
Bake at 400°F. for 15 to 25 minutes or until light golden brown. Cut into wedges. Serve warm.