2tablespoonsblack sesame seeds, plus ½ cup for rolling
1cupdark chocolate chips or chunks
1cupmilk chocolate chips or chunks
Whisk together the flour, baking soda and salt. Set aside. In the bowl of a mixer fitted with a paddle attachment, beat together the butter and sugars until light and fluffy, about 3 minutes. Add the egg and egg yolk, vanilla, sesame oil and soy sauce and beat until light, another 2 minutes.
Stir in the dry ingredients, mixing slowly until the flour is incorporated and then beat on low speed until completely mixed; scraping the bottom and sides of the bowl as needed. Add the 2 tablespoons sesame seeds and chocolate, and stir together until well combined.
Use a spoon or cookie scoop to form dough into ¼-cup-sized balls and roll in black sesame seeds. Place on a parchment-lined baking sheet and cover or place in a zip top bag and refrigerate cookies for 1 hour or overnight.
Heat the oven to 350ºF and line baking sheets with parchment. Place chilled cookies on prepared baking sheets and bake until just set in the center and lightly golden on the edges, 14 to 16 minutes. Allow to cool on the baking sheet for about 10 minutes, then remove to cool completely. Store cookies in an airtight container.
If you choose to use salted butter in these cookies, simply reduce the added salt to about a ½ teaspoon instead of 1½ teaspoons.