Preheat oven to 350°. Line several baking sheets with parchment paper.
In a small bowl, whisk together egg white and 1 teaspoon water. Set aside for brushing tops of cookies.
In the container of a blender, pulse together granulated sugar, lemon zest, herbes de Provence, and salt until herbs are ground.
In a large bowl, beat together butter, confectioners’ sugar, and granulated sugar mixture with a mixer at medium speed until blended, stopping to scrape sides of bowl as necessary. Add egg yolk, beating until blended. Gradually add flour, beating until a dough begins to form. Using hands, knead dough in bowl until a smooth dough forms.
On a lightly floured surface, roll out dough to a ⅛-inch thickness. Using a fluted 2¼-inch round cutter dipped in flour, cut approximately 48 cookies from dough. Place cookies 1 inch apart on prepared baking sheets. Lightly brush with egg white mixture. Lightly sprinkle with sanding sugar.
Bake until cookie edges are golden brown, 8 to 11 minutes. Remove from baking sheets, and let cool completely on wire racks.
Recipe by TeaTime Magazine at https://teatimemagazine.com/herbes-de-provence-sables/