Slice Japanese eggplant on the diagonal 3/4 to 1 inch thick, larger pieces cut in half lengthwise.
Put the eggplant in a colander in the sink or over a bowl, toss with approximately tablespoon of salt, and set aside to drain for about 45 minutes. Rinse the eggplant thoroughly, pat dry, and transfer to a large bowl.
Sprinkle the cornstarch over the eggplant and toss to coat. Heat the oil in a 12-inch skillet or wok over medium-high heat. Add just enough eggplant to create a single layer so that no slices overlap. Cook, flipping once, until the eggplant is golden and a bit charred in places, 2-1/2 to 3 minutes total. Transfer the eggplant to a paper-towel-lined rimmed baking sheet. Repeat with the remaining eggplant, adding more oil to the pan as needed.
Wipe the pan clean, then add the sesame oil over low heat. Add the garlic and ginger, and cook, stirring, until fragrant, about 20 seconds. Return the eggplant to the pan.
Add the Thai basil leaves, red chili, soy sauce, Maggi sauce, oyster sauce and fish sauce then toss to combine, about 1 minute.
Serve topped with the sliced scallion.