Step 1

Slice the eggplant on the diagonal 3/4 to 1 inch thick, larger pieces cut in half lengthwise. Transfer the eggplant slices to a medium bowl,  sprinkle with the cornstarch, and toss to coat evenly. 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.

Step 2

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 soy sauce, and toss to combine, about 1 minute. Serve topped with the scallion, and season to taste with more soy sauce.