Preheat broiler with the rack about 4 inches from the heat source.
Line the baking pan with parchment paper and spray it with non-stick cooking spray.
In a small bowl, combine miso, sugar, mirin, and red chili pepper flakes and mix well. Set aside.
Remove the ends of the eggplants. Slice them in half lengthwise from the stem to bottom creating boat-like halves. If you use Chinese eggplants, cut each boat-like half crosswise for a good size.
With the tip of a knife score the flesh, about 1/4 inch deep 3-4 times across the eggplants.
Place the eggplants flesh side down and broil until the outer skin browns and softens, about 5 minutes. Turn the eggplants flesh side up and brush on the mixture from step 3.
Broil the eggplant again until glaze starts to brown and sizzle, about 5 minutes.
Sprinkle with sesame seeds, green onion, and cilantro. Serve immediately.