Gather all the ingredients. Set the rack in the center of the oven about 7 inches (18 cm) away from the heating element. Preheat the oven to 425ºF (220ºC). For convection, reduce the temperature by 25ºF (15ºC).

Combine 3 Tbsp miso and 1 Tbsp sugar in a small bowl. Mix well to dissolve the sugar.

Add 1 Tbsp mirin and ½ Tbsp sake and stir. If needed, you can add a bit more sake until you reach your preferred consistency, as some miso is chunkier than others. Mix well and set aside.

Cut off the stem and calyx of 3 Japanese eggplants. Cut the eggplants in half lengthwise from stem to tip, creating boat-like halves. If your eggplants are long, you can cut them in half crosswise so they're shorter.

With the knife, score the cut surface of eggplant diagonally about ⅛ inch (3 mm) deep and apart. Work in one direction first and then the other, creating a crisscross pattern on the flesh.

Soak them in water for 10 minutes to remove the astringency. Blot them with paper towels or a clean kitchen towel and place on a baking sheet lined with parchment paper.

Brush the cut surface with 1 Tbsp toasted sesame oil. Turn them over so they are cut side down on the baking sheet.

Bake the eggplants at 425ºF (220ºC) for 15 minutes.

Meanwhile, cut 1 green onion/scallion into thin rounds. Roll up 5 shiso leaves (perilla/ooba) and cut them into julienned strips.

After 15 minutes, the eggplant flesh should be soft and the skin slightly shriveled. Remove the baking sheet from the oven. Now, preheat the broiler.

Carefully turn the eggplants cut side up and brush the flesh with a layer of sweet miso glaze. Coat the surface completely.

Place the eggplants under the broiler until the glaze begins to bubble and caramelize, about 3–5 minutes. Remove from the broiler.

Sprinkle the baked eggplants with 2 tsp toasted white sesame seeds, sliced green onions, and julienned shiso leaves. Serve immediately.