Preheat oven to 350°F (175°C). Lightly grease a large baking sheet. In a small bowl, blend the sour cream and baking soda, and set aside.
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. Mix in the raisins.
Turn dough out onto a lightly floured surface, and knead briefly. Roll or pat dough into a 3/4-inch-thick round. Cut into 12 wedges, and place them 2 inches apart on the prepared baking sheet. Sprinkle scones with raw sugar.
Bake 15-20 minutes in the preheated oven, until golden brown on the bottom.
Notes
Nutrition estimate does not include the raw sugar for sprinkling.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.