Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a small bowl, combine lemon zest with granulated sugar. Let it sit for a few minutes to infuse.
In a mixing bowl, cream the butter with lemon sugar until light and fluffy.
Add in the egg, lemon juice, and vanilla extract. Mix well.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually mix the dry ingredients into the wet mixture until a soft dough forms.
Roll the dough into 1-inch balls and coat in granulated sugar.
Place dough balls on the prepared baking sheet, leaving space between each.
Bake for 9–11 minutes, or until the edges are lightly golden.
Let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack.
Enjoy warm or store in an airtight container for up to 5 days.