Line rimmed baking sheets with silicone baking mats, or coat them lightly with vegetable oil. Set aside.
In a medium sauté pan, toast sesame seeds over medium heat, stirring frequently, until light golden brown. Let cool.
In a small bowl, combine flour, salt, and baking powder, whisking to blend. Set aside.
In a large bowl, beat butter and brown sugar at medium speed with an electric mixer until light and fluffy, approximately 2 minutes. Add egg, lemon zest, and vanilla extract, beating until incorporated. Add flour mixture, beating until incorporated. Add sesame seeds, stirring to combine.
Using a levered 1-teaspoon scoop, drop cookies 3 inches apart onto prepared baking sheets. (Cookies will spread.)
Bake until cookies are deep golden brown, approximately 15 minutes per batch. Let cookies sit on baking sheets for 1 minute. Transfer to wire cooling racks, and let cool completely.
Notes
Make-Ahead Tip: Cookies can be made a week in advance and frozen in an airtight container. Separate layers with waxed paper.
Recipe by TeaTime Magazine at https://teatimemagazine.com/benne-wafers-recipe/