Toasted Sesame Cookies

We are late to the cookie banging party, and Sarah Kieffer's new book 100 Cookies, which we had some delay in being able to obtain--I guess with everyone home cooking and baking, cookbooks will go through an uptick of popularity--but now we have it and we are off and running.  These are beautiful and unusual to look at and delicious to eat.

• 1 ³/₄ cups (249 grams) all-purpose flour
  
• ³/₄ teaspoon salt
  
• ¹/₂ teaspoon baking soda
  
• 12 tablespoons (1 1/2 sticks or 170 grams) unsalted butter, at room temperature
  
• 1 cup (200 grams) granulated sugar
  
• ¹/₂ cup (100 grams) brown sugar
  
• 1 large egg
  
• 2 tablespoons toasted sesame oil
  
• 1 tablespoon water
  
• 1 ¹/₂ teaspoons pure vanilla extract
  
• 3 ounces (85 grams) bittersweet or semisweet chocolate, chopped into bite-size pieces (averaging 1/2-inch with some smaller and some larger, optional)
  
• Black and white sesame seeds, for rolling

1. Adjust an oven rack to the middle of the oven. Heat the oven to 350°F (180°C). Line three sheet pans with aluminum foil, dull-side up.
2. In a small bowl, whisk together the flour, salt, and baking soda.
3. In the bowl of a stand mixer fitted with a paddle, beat the butter on medium speed until creamy, about 1 minute. Add the granulated and brown sugars and beat on medium speed until light and fluffy, 2 to 3 minutes. Add the egg, toasted sesame oil, water, and vanilla, and mix on low speed to combine. Add the flour mixture and mix on low speed until combined. Add the chocolate, if using, and mix until combined.
4. Form the dough into 3-ounce (85-gram) balls (1/4 cup). Roll in the sesame seeds, and place 4 cookies an equal distance apart on each sheet pan. Bake the cookies one pan at a time. Bake until the dough balls have spread flat but are puffed slightly in the center, 9 minutes. Lift one side of the sheet pan up about 4 inches (10 centimeters) and gently let it drop down against the oven rack, so the edges of the cookies set and the center falls back down. After the cookies puff up again in 2 minutes, repeat lifting and dropping the pan. Repeat a few more times to create ridges around the edge of the cookie. Bake for 15 to 16 minutes total, until the cookies have spread out and the edges are golden brown but the centers are much lighter and not fully cooked.
5. Transfer the pan to a wire rack. Let the cookies cool for 10 minutes, then move them to a wire rack to finish cooling. Store cookies in an airtight container at room temperature for 2 days (or refrigerate for up to 3 days).