Wonderful, traditional style scones. Goes great with coffee and tea. You can experiment with different fruit. Fruit can be fresh, frozen or dried. I particularly like using fresh blueberries when they are plentiful in the summer.
In a small bowl, blend the sour cream and baking soda and set aside.
Preheat oven to 350 degrees. Lightly grease a large baking sheet.
In a large bowl, mix the flour, sugar, baking powder, cream of tartar and salt. Cut in the butter. Stir the sour cream mixture and egg into the flour mixture until just moistened. Gently fold in the blueberries (or fruit of your choice).
Halve the dough. Turn one half dough out onto a lightly floured surface and knead briefly. Roll or pat dough into a 3/4" thick round. Sprinkle with sugar. Cut into 8 wedges and place them 2" apart on baking sheet (they will expand).
Bake 12 - 15 minutes in preheated oven, until golden brown on the bottom.