Preheat your oven to 400°F (200°C) or preheat your grill to medium-high heat.
Slice the eggplant into 1/2-inch thick rounds. If using a grill, brush the eggplant slices with a little oil to prevent sticking.
In a small bowl, whisk together the miso paste, soy sauce, honey or maple syrup, rice vinegar, sesame oil, grated ginger, and minced garlic until well combined.
Place the eggplant slices on a baking sheet or grill grates and brush both sides generously with the miso glaze.
If using the oven, roast the eggplant for about 20-25 minutes, flipping halfway through, until tender and slightly caramelized. If using the grill, cook the eggplant for about 4-5 minutes per side until tender and grill marks appear.
Once cooked, remove the eggplant from the oven or grill and transfer to a serving plate.
Sprinkle the roasted or grilled eggplant slices with sesame seeds and chopped green onions.
Serve the miso-glazed eggplant as a side dish or as a main course with steamed rice or noodles.