Thoroughly clean the milkfish and pat dry. Season with salt and fry until golden brown and set a side.
In a pan, combine pork fat and water. Boil and simmer for 30 minutes or until the fat is tender.
Increase heat until the water evaporates and the oil oozes out from the pork fat. Stir fry until fat is golden brown.
Sauté garlic and onion.
Add miso paste and rice wash. Stir to dissolve miso paste. Boil and simmer for 10 minutes.
Add sinigang mix and fried milkfish. Season with fish sauce, ground black pepper and green chili. Simmer for another 10 minutes.
Add mustard leaves and simmer for 3 minutes.