Combine flour, sugar, salt baking powder and cream of tartar in large bowl.
Cut in cold butter.
Stir in dried fruit and nuts.
In a separate bowl combine sour cream and baking soda. Mix to combine and let rest 5 minutes.
Add egg and sour cream to baking soda/egg mixture.
Combine dry and wet ingredients to moisten.
Press crumbly dough into 1/4 sheet baking pan and roll to flatten.
Cut the dough int 4x4 squares then cut each square from corner to corner to create individual triangles.
Freeze scone dough for up to one month.
Place scones on parchment lined sheet pan and bake at 400 degrees F for 14 minutes or until golden in color.