Heat oven to 350°F; line baking sheets with parchment.
Whisk flour, baking powder, and salt in a medium bowl; set aside.
Beat butter and granulated sugar in a large bowl about 3 minutes until light and fluffy. Beat in egg, lemon juice, zest, and vanilla.
Gradually mix dry ingredients into wet just until combined; dough will be slightly sticky.
Put powdered sugar in a shallow bowl. Scoop rounded tablespoons of dough; roll into balls and coat generously in sugar.
Space cookies 2 inches apart on sheets. Bake 10-12 minutes until edges set and cookies crackle; centers will look slightly underdone. Cool on sheet 5 minutes; transfer to a rack.