Line two cookie sheets with parchment paper. In a medium bowl whisk together flour, kosher salt, baking soda, and baking powder.Advertisement
In a large bowl beat brown sugar, butter, shortening, 1/4 cup granulated sugar, and the vanilla on medium until combined. Add egg and egg yolks; beat on low until combined. Add tahini; beat on medium until combined. Add flour mixture. Beat on low until combined.
Chill, covered, 30 minutes or until firm enough to handle. Roll into 2-teaspoon balls (1 1/4 inches). Place remaining 1/2 cup granulated sugar in a small bowl. Roll balls in sugar to coat. Arrange on a prepared cookie sheet. Sprinkle with sea salt. Cover with plastic wrap. Freeze 2 hours or until firm.
Preheat oven to 350°F. Transfer 16 dough balls to remaining cookie sheet. Bake 10 to 12 minutes or until light brown, rotating sheet halfway through. Immediately after removing from oven, gently press a Kiss in the center of each cookie. Let cool on a wire rack. Repeat with remaining dough balls. Store in an airtight container at room temperature up to 3 days. Makes 60 cookies.