Mix all the sauce ingredients in a small bowl. Set aside.
Heat a wok or large pan over medium-high heat. Add eggplant and 2 tablespoons water. Cover and steam for about 3 minutes, until slightly softened.
Uncover and let the water evaporate. Add 2 tablespoons oil and sear for about 3 minutes, turning until lightly browned and tender but not mushy. Transfer to a plate.
Raise the heat to high and add a little oil if needed. Lightly salt the shrimp and sear about a minute per side, until pink and opaque. Transfer to a plate.
Lower the heat to medium-high. Cook garlic, ginger, and optional chilies for 30 seconds. Add bell pepper, onion, and scallion whites. Stir-fry for 1–2 minutes, until tender-crisp.
Return eggplant and shrimp to the pan. Add scallion greens. Stir the sauce again, then pour it in.
Gently toss for about a minute, until the sauce bubbles and thickens. Add a splash of water if too thick. Add pepper;taste and adjust. Turn off the heat.
Notes
Eggplant: Use Chinese or Japanese eggplant for thinner skin and fewer seeds. No need to peel.
Shrimp: Use large, peeled and deveined shrimp. Substitute chicken, beef, or tofu; cook separately before adding back.
Shaoxing wine: Substitute dry sherry or leave it out.
Sesame oil: Adds a nutty flavor. Use toasted, not regular sesame oil, or leave it out.
Chilies: Use bird’s eye chilies or red pepper flakes, or leave them out.