Preheat oven to 400 degrees Fahrenheit.
In a large bowl, beat the sugar and butter on high speed with an electric mixer until it’s smooth.
Add the eggs and vanilla and beat on medium speed until just combined.
In a separate small bowl, mix the sour cream and baking soda together. Set aside.
In a medium bowl, combine the flour, salt, and baking powder together.
Alternate beating in the sour cream mixture and the flour mixture into the creamed sugar and butter until everything is combined. If you don’t have a stand mixer, you will have to mix the flour in by hand eventually. Just knead the flour into the dough until there are no streaks.
Roll out the dough onto a lightly floured surface until it is 1/4 of an inch thick. You might have to add more flour depending on the texture of the dough. If you roll it out and try to cut out shapes but the dough stretches and breaks, you need to add more flour. Keep adding flour, kneading, and rolling it out until you can cut out sturdy shapes.
Cut out the dough into various shapes. Take the leftover dough, roll it into a ball, and roll it out again to cut out more shapes. Repeat until there is no dough left.
Bake on cookie sheets for 5 to 7 minutes. The bottoms should be a very light brown color and the tops should still be pure white. They won't look cooked. Transfer to cooling racks and let the cookies cool completely before frosting. Store unfrosted cookies in an airtight container or in a ziplock bag.