Whisk together flour, baking soda, and salt

Combine and butter and sugar in a large mixing bowl and beat until light and fluffy, about 5 minutes

Beat in the egg into the sugar mixture

Mix in the sour cream and vanilla

Mix in the flour mixture until just combined

Sprinkle flour onto a large work surface, place the dough onto the surface, and then use a rolling pin to form it into a disc

Wrap the disc in plastic wrap and refrigerate for 1 hour

Preheat the oven to 300 F

Line two baking sheets with parchment paper

On the floured work surface, roll out the chilled dough until 1/2 inch thick. Use your cookie cutters to cut out the cookies. Reform the dough into a disk until all of it has been used

Bake the sugar cookies, 1 sheet at a time, for 8-10 minutes. Let the cookies cool for at least 20 minutes before serving