Preheat the oven to (350°F) = (176 C°) degrees.
In a large bowl, cream the sugar, butter, sour cream, eggs, and vanilla.
Add the baking soda and salt.
Gradually add the flour and mix until thoroughly combined.
If you want to make the cookies later, wrap the dough in plastic wrap and put it in the refrigerator.
Sprinkle flour on the counter you will roll the cookie dough onto. Sprinkle the rolling pin as well.
I like my cookies thick and chewy so I rolled my dough out 3/8 inches thick. I used cookie cutters approx. 4-5 inches in diameter.
I baked mine for 15 minutes. Do not overbake. I watched the cookies for the last two minutes to make sure they did not brown.
Wait to make the frosting until right before you frost them. It hardens up very quickly.
Beat the egg whites until fluffy and thick.
Add the powdered sugar and cream of tartar.
Add food coloring if desired.
Frost quickly as it thickens when dry. Sprinkle with "sprinkle" if desired.