Score flesh of eggplant and sprinkle with kosher salt. Lay cut side down on paper towel lined sheet pan. Let them sit for 45 - 60 minutes.
Flip over and using clean paper towels or kitchen towel, wipe off excess salt and excess liquid from eggplant. (If you do not remove the salt, the eggplant may taste too salty!)
In a small bowl, whisk together the miso, ginger, sesame oil, soy sauce, rice vinegar, brown sugar, red pepper flakes (if using) and a tablespoon of water, if needed to loosen mixture. Set aside.
Heat grill to medium high (450°F - 475°F). Place eggplant cut side down on grill (do not oil). Cook for 4 - 6 minutes, then turn over and cook for another 4 minutes. (Watch it carefully, as sugar can burn)
Brush miso glaze onto eggplant and cook for an additional 2 minutes.
Remove from grill, sprinkle with sesame seeds and cilantro.