Preheat the oven to 350˚F. Lightly spray cookie sheets, and set aside.
In a large bowl, beat together the egg yolks and sugar. Mix in the sour cream until smooth.
In a small bowl, add the baking soda and the vinegar to get it to bubble, and mix together. Add in the salt and vanilla.
Mix in the vinegar mixture to the sugar mixture until fully combined.
Slowly add in the flour, and mix with a fork until fully combined. Dough will be a little sticky.
Lightly flour hands, and scoop one heaping teaspoon of dough into hands, and form into balls. Place on the prepared cookie sheet.
Bake in the preheated oven to 25-30 minutes, or until beginning to golden. Remove immediately.
Meanwhile, beat together the egg whites in a medium bowl with an electric beater on high until tripled in volume.
Reduce the speed to low, and add in the powdered sugar, lemon juice and peppermint extract until well blended.
Set to medium speed and mix for about 2 minutes until creamy. Do not beat too much or it will become watery.