Preheat oven to 350 degrees F. Line two baking sheets with parchment and set aside. On a plate or shallow bowl, combine the sugar and sesame seeds. Set aside.
In a medium bowl, whisk together the flour, baking powder and baking soda.
In the bowl of a stand-up mixer with the paddle attachment (you could also do this in a large bowl with an electric hand mixer), add the butter, peanut butter and miso. Blend until very smooth, about 2 minutes. Add the brown sugar, white sugar and vanilla; cream together for a full 2 minutes, until very creamy and a light pale brown color. Add in the egg and vanilla and blend one last time.
Pour in the flour all at once and mix on low (so the flour doesn’t fly out) until you no longer see any speckles of flour. Using a medium (2 ounce) cookie scoop, scoop out balls of dough and roll them in between your palms to form a ball. Roll them in the sugar/sesame mixture and transfer them to the baking sheet about 5-inches apart.
You’ll have to do this in batches. Using the tines of a fork, press down to flatten slightly and then turn the fork perpendicular and flatten them slightly again. This should form a criss cross pattern.
Bake the cookies, one sheet at a time, for about 9-11 minutes. Just until the edges are lightly golden brown. Let them cool on the baking sheet for 5 minutes before moving them to a cooling rack. Repeat with the remaining cookies.
Store the cookies in an airtight container for up to 4 days.