Steps
- Preheat the oven to 350°F / 175°C and line baking sheets with parchment. Separate 2 large pasteurized eggs. Whisk the yolks with 2 cups of sugar, then whisk in 2 cups of sour cream.
- Mix 1 teaspoon of baking soda with ½ teaspoon of white vinegar. Whisk into the batter with ½ teaspoon of salt and 1 teaspoon of vanilla extract.
- Gradually mix in 5 cups of all-purpose flour with a dough hook until combined. With floured hands, form golf-ball-sized rounds, flatten slightly, and place on the sheets.
- Bake for 25-28 minutes, until just beginning to turn golden. Meanwhile, whisk the reserved whites on high for 2-3 minutes, until thick and tripled in volume.
- On low speed, mix in 2 cups of icing sugar, 1 teaspoon of peppermint extract, and 1 teaspoon of lemon juice. Beat on medium for about 2 minutes, until creamy.
- Coat the hot cookie tops with glaze and leave on a cool, dry surface until firm. Turn over, glaze the bottoms, and leave until the entire coating sets.