01 - Beat softened butter and powdered sugar in large bowl until light and fluffy, approximately 3 minutes.
02 - Incorporate lemon juice, zest, and vanilla extract until fully blended.
03 - Mix in salt, flour, and cornstarch until soft dough comes together.
04 - Divide dough in half, roll into 1-inch diameter logs, wrap in plastic, refrigerate 30 minutes.
05 - Preheat oven to 350°F. Line baking sheets with parchment paper.
06 - Unwrap dough, cut into 1/4-inch rounds, arrange 1 inch apart on prepared sheets.
07 - Bake 10-12 minutes until edges turn light golden.
08 - Cool on sheets 5 minutes, gently toss in powdered sugar while warm.
09 - Transfer to wire rack, cool completely, dust with extra powdered sugar before serving.