Whisk the water, soy sauce, dry sherry, sugar, cornstarch, and red pepper flakes together in a small bowl until the sugar and cornstarch are completely dissolved.

Mix a teaspoon of oil with the minced garlic and grated ginger in a separate small bowl. Heat the remaining oil in a 12-inch nonstick skillet over high heat until it shimmers and is just beginning to smoke.

Add the eggplant and bell pepper to the skillet and cook, stirring frequently, until the vegetables are tender and the eggplant shows deep brown charred spots, 8 to 10 minutes.

Clear a space in the center of the skillet and add the garlic-ginger mixture. Cook while mashing the aromatics into the pan until fragrant, about 30 seconds, then stir them into the rest of the vegetables.

Whisk the sauce briefly to recombine any settled starch, then pour it into the skillet. Cook, stirring constantly, until the sauce thickens into a glossy glaze that coats the vegetables, about 30 seconds.

Remove the pan from the heat and fold in the fresh basil and scallions. Serve immediately, while the vegetables are hot and the sauce is vibrant.