Line the bottom of a wide pot with half the ginger, garlic and onion, place the fish on top, then the aubergine, bitter melon, chilli and the rest of the spiced onion.
Pour in the vinegar and water, add the pepper and fish sauce.
Bring to the boil uncovered, and boil without stirring for 3-4 minutes, so the sharp edge of the vinegar cooks off.
Then cover, and simmer over low heat for 15-20 minutes, until the fish is cooked through and the vegetables are tender. Don't stir, just shake the pot gently so the fish doesn't break up.
Taste and season with salt as needed. Serve with rice; even better the next day.
A Receptnaptár original recipe. Calories and protein are estimated.
Tips
Don't stir for a few minutes after adding the vinegar, and don't cover it yet, so the flavour mellows.