Grandma Johnson's Lemon Scones

I don't remember where I got this recipe, but it's my favorite scone recipe.

1 c. sour cream

Before going into the oven

1 tsp. baking soda
4 c. flour
1 c. sugar
2 tsp. baking powder
1/4 tsp. cream of tartar
1 tsp. salt
1 c. butter
1 egg
1-2 Tbsp. lemon zest

Fresh out of the oven

Preheat oven to 350 F. Lightly grease 2 baking sheets. In a small bowl, stir together sour cream and baking soda. In a large bowl, combine flour, sugar, baking powder, cream of tartar, and salt. Cut in butter with a knife or a pastry blender (I also hear grating very cold butter works great). Combine egg with sour cream mixture. Add the lemon zest into the flour mixture. Stir the sour cream mixture into flour mixture until moistened. Turn dough out onto a lightly floured surface. Knead briefly. Roll dough out into a 3/4 in thick round. Cut into 12 wedges and bake for 12-15 minutes or until golden brown. I used a scone pan, and made 15 scones with this recipe.