In a stand mixer or another large bowl, combine the sugar and lemon zest. Rub the mixture together for a minute between your fingers, so the zest incorporates into the sugar and infuses it with flavor.
Add butter and beat on medium-high speed for 2-3 minutes, until the mixture is light and fluffy. Add egg, lemon juice, and vanilla. Scrape down the sides of the bowl and beat again until well-combined.
Sprinkle flour, baking soda, and salt over the mixture. Beat on medium-low speed just until the streaks of flour disappear. Place dough in the refrigerator to chill for about 1 hour.
When ready to bake, preheat oven to 350 degrees F. Prepare two baking sheets by lining with parchment paper or silicone baking mats.
Scoop the chilled dough out into mounds of about 1 and 1/2 tablespoons each and place on baking sheets. For more even cookies, roll each into a smooth ball. (This isn't necessary, just depends on what you prefer.)
Bake for 10-12 minutes, until the edges are very slightly browned and the tops are set. Let cool for 10-15 minutes on the baking sheets before transferring cookies to a wire rack. Sprinkle with extra lemon zest or sparkling sugar, if desired. Enjoy!
Notes
Chilling: It’s important to chill this dough so the cookies don’t spread out too much while baking and maintain their soft, chewy texture.
Lining the Pans: It’s helpful to line your baking sheets with silicone mats or parchment paper, both because they make clean-up easy and because they help cookies brown nicely, but not too much or too quickly, on the bottom.
Cookie Scoop: I use this cookie scoop for this and countless other recipes.
Storage: Cookies keep well covered at room temperature for 3-4 days.