Line a sheet pan with paper towels. Cut the eggplants in half lengthwise. To score the flesh, use a paring knife to cut diagonal lines about 1 inch (2.5 cm) apart, without cutting through the skin. Turn and cut diagonal lines in the other direction, resulting in a diamond pattern. Generously salt the eggplants and lay them flesh side down. Let the eggplants sit for at least 1 hour.
Preheat the oven to 400°F (204°C). Line a half sheet pan with parchment paper.
Pat the eggplants with a clean paper towel to absorb any remaining water. Lightly brush the eggplants all over with sunflower oil and place them cut side down on the sheet pan. Bake for 20 minutes, until the flesh is soft and golden brown.
In the meantime, make the miso glaze. In a small mixing bowl, add the miso, sunflower oil, mirin, tamari and apple cider vinegar. Break up the miso with a small silicone spatula and whisk it together until completely smooth.
Take the eggplants out of the oven and turn the oven to the broiler setting.
Turn the eggplants over and brush the flesh with the miso glaze, coating the entire surface. Broil until the glaze has caramelized and is charred in spots, about 5 to 8 minutes.
Serve topped with scallions and sesame seeds.