Arrange the onion, fish, ginger, whole peppercorn, water, and vinegar in a cooking pot. Cover the pot and turn the heat on. Let the liquid boil.
Once the liquid starts to boil, adjust the heat to low. Cook for 15 minutes.
Add the eggplant, bitter gourd, and chili (or pepper). Cover the pot and continue to cook until the water completely evaporates.
Transfer to a serving plate. Serve.
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