Add all the glazing ingredients to a small bowl (miso, mirin, olive oil) and whisk to combine. Cut the eggplant in half lengthwise and score the inside flesh of each half with a knife in a crisscross pattern.
Get a pan going over high heat and add your oil to coat the bottom of the pan. Place your eggplant in the pan with the outer skin side facing down. Cook for a few minutes until the skin begins to brown.
Turn the eggplant over and cover with a lid. Cook until eggplant is cooked through (3-4 minutes).
Preheat the oven to 230℃/446°F. Line the baking tray with aluminum foil and place the eggplant skin side facing down. Spread the sauce mixed in step 1 evenly on the surface of the eggplant.
Finish by sprinkling with sesame seeds and chopped green onions.