1.  Adjust an oven rack to the middle of the oven. Preheat oven to 350F. Line three sheet pans with aluminum foil, dull-side up.

2.  In small bowl, whisk together flour, salt, and baking soda.

3.  In the bowl of a stand mixer fitted with a paddle, beat butter on medium speed until creamy, about 1 minute. Add granulated and brown sugars and beat on medium speed until light and fluffy, 2 to 3 minutes. Add egg, toasted sesame oil, water, and vanilla, and mix on low speed to combine. Add flour mixture and mix on low speed until combined. Add chocolate, if using, and mix until combined.

4.  Form dough into 3 oz balls (¼ cup). Roll in sesame seeds and place 4 cookies an equal distance apart on each sheet pan. Bake one pan at a time and until 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 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 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 pan to wire rack. Let cookies cool 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).

Reprinted from 100 Cookies by Sarah Kieffer with permission by Chronicle Books, 2020.