Prepare flax egg by combining the flaxseed and water. Mix and set aside for two minutes. Line a cookie sheet with parchment paper.
In a large bowl, whisk tahini, maple syrup, and flax egg together until well combined. Add flour, cocoa powder, coconut sugar, baking powder, baking soda, salt, and vanilla extract. Stir until fully combined. Fold in chocolate chips. Cover bowl with plastic wrap and chill in refrigerator for at least 1-2 hours.
Assembly: Preheat oven to 350 degrees Fahrenheit. Place the sesame seeds in a small bowl. Fill another small bowl with water. The cookie dough will be sticky, so spray your hands with cooking spray or get them damp, then using a small spoon or cookie scooper, scoop cookie dough and gently roll into a loose ball with your hands. Dip or roll each ball into sesame seeds and place on cookie sheet. Dip a fork into the water and press down slightly vertically and then horizontally on top of ball. Re-wet your fork after a couple cookies so it doesn’t stick. This is not to get a tines marking on your cookies, rather, it is to ensure they spread into a more even circle during baking.
Bake for 10 to 12 minutes. Remove from oven and wait 3 minutes before transferring cookies to a wire rack.
Enjoy!