01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk flour, baking soda, and salt in medium bowl. Set aside.
03 - Beat butter and sugar until light and fluffy, about 2-3 minutes.
04 - Beat in lemon zest, egg, lemon juice, and vanilla until fully incorporated.
05 - Gradually add dry ingredients to wet mixture, mixing just until combined.
06 - Scoop tablespoon-sized dough balls and roll each in extra sugar to coat.
07 - Place cookies 2 inches apart on prepared baking sheets.
08 - Bake for 9-11 minutes until edges are lightly golden and centers are set.
09 - Cool on sheet for 5 minutes, then transfer to wire rack to cool completely.