Pour the butter into a medium bowl and stir in ¼ cup of sugar, 1 tablespoon lemon zest, vanilla, and egg.
In a large bowl, combine the flour, cornmeal, baking powder, and salt and stir to combine. Add the butter-egg mixture to the dry ingredients and mix until well combined. Refrigerate the dough until firm, about 1 hour or up to overnight. If refrigerating overnight, store in an airtight container.
Place a rack in the center of the oven and preheat to 350°F. Line a baking sheet with parchment paper.
Make the dipping mix: In a small bowl, combine 2 tablespoons sugar, pistachios, and 1 tablespoon lemon zest. Roll the cookie dough into balls the size of a large walnut. Roll the dough balls around in the dipping mix, pressing firmly to allow the sugar mix to adhere to the cookies. (You’ll likely end up with a little dipping mix left over.)
Place the cookies on the prepared baking sheet about 2 in apart. Press them flat with the palm of your hand; these don’t spread very much on their own. Bake for 15 to 18 minutes, or until they are golden brown on the edges and pale in the center and baked through. Remove the cookies from the oven and let them cool on the sheet for 5 to 10 minutes, then transfer the cookies to a wire rack to cool completely.
The cookies can be stored at room temperature in an airtight container for up to 2 days. The unbaked dough can be stored in an air tight container in the refrigerator for up to 1 week or in the freezer for up to 3 weeks (add a few minutes to the baking time if you are baking straight from the freezer); the sugar dipping mix can be stored in an airtight container at room temperature for up to 1 week.
(This recipe is excerpted with permission from Baking with Less Sugar by Joanne Chang, Chronicle Books copyright © 2015)
Baking with Less Sugar