01 - Beat softened butter and powdered sugar in large bowl until light and fluffy, approximately 2-3 minutes.
02 - Mix in lemon juice, lemon zest, and vanilla extract until thoroughly combined.
03 - Add salt, flour, and cornstarch, mixing until soft dough forms.
04 - Divide dough in half, roll each half into 1-inch diameter logs, wrap in plastic, and refrigerate for minimum 30 minutes.
05 - Preheat oven to 350°F and line two baking sheets with parchment paper.
06 - Unwrap chilled dough, slice into 1/4-inch rounds, and place on prepared baking sheets 1 inch apart.
07 - Bake for 10-12 minutes until edges are just barely golden.
08 - Let cool on baking sheets for 5 minutes, then gently toss warm cookies in powdered sugar.
09 - Transfer cookies to wire rack to cool completely. Dust with additional powdered sugar before serving if desired.