01 - In a large bowl, beat softened butter and powdered sugar until light and fluffy using an electric mixer.
02 - Mix in lemon juice, lemon zest, and vanilla extract until fully incorporated.
03 - Add salt, flour, and cornstarch, mixing until a soft dough forms.
04 - Divide dough in half and roll each half into a 1-inch diameter log. Wrap in plastic and refrigerate for at least 30 minutes.
05 - Preheat oven to 350°F and line two baking sheets with parchment paper.
06 - Unwrap dough and slice into 1/4-inch rounds. Place cookies 1 inch apart on prepared baking sheets.
07 - Bake for 10-12 minutes until edges are barely golden.
08 - Let cool on baking sheets for 5 minutes, then gently toss warm cookies in powdered sugar.
09 - Transfer cookies to a wire rack and cool completely. Dust with additional powdered sugar before serving.