In bowl whisk together brown sugar, soy sauce, sesame oil and miso paste until well combined.
Pour into a plastic bag with chicken and smoosh it all together ensuring all the chicken is coated. Seal bag and place in refridgerator for a minimum 30 minutes up to over night.
About thirty minutes before you are ready to serve dinner preheat the oven to 450 F. Slice potatoes into 1/4 inch thick slices. Put in a bowl and toss with olive oil, a good sprinkle of salt and pepper. Lay out onto parchment lined baking sheet big enough to hold one layer.
Roast potatoes for 7 minutes then turn over and roast for another 8 minutes for a total of 15 minutes. Remove from oven.
Carefully remove chicken from marinade (keep) and lay on top of potatoes. Pour remaining marinade all over.
Roast chicken for an additional 20 minutes or until the chicken is cooked through.
To serve sprinkle with sesame seeds, green onion and cilantro.