Preparation

• Whisk the flour, cornstarch, baking soda, and salt together in a medium bowl. Set aside.
• In a large bowl, beat the butter and granulated sugar together until creamed, about 3 minutes. Add the egg, lemon juice, lemon zest, and vanilla extract, and beat until combined, about 1 minute.
• Add the flour mixture and beat on low speed until combined. The dough is thick, creamy, and sticky.
• Cover dough tightly and chill in the refrigerator for at least 3 hours and up to 3 days.
• Remove cookie dough from the refrigerator. Let sit at room temperature for about 10 minutes if chilled longer than 3 hours.
• Preheat oven to 350°F (177°C) and line baking sheets with parchment paper.
• Roll balls of dough into about 1 tablespoon each, optionally rolling in granulated sugar before confectioners’ sugar. Place on baking sheets 3 inches apart.
• Bake for 12–13 minutes or until edges appear set and centers look soft. Cool for 5 minutes on the baking sheet.
• Transfer to a cooling rack to cool completely.