Thoroughly clean the fish and pat dry.
Season the fish with salt and fry until golden brown and set a side.
Heat pressure cooker and add olive oil. Sauté ginger, garlic and onion.
Add the miso paste and stir until golden in color.
Add the tomatoes and half cup of water. Simmer until tomatoes are tender. Mashed the tomatoes using the back of your wooden spoon.
Add the remaining water and season with fish sauce and ground black pepper.
Boil and cover the pressure cooker. Cook for an hour over medium low heat.
Add the sinigang mix with gabi and season with fish sauce.
Lastly, add the mustard leaves and simmer for 5 minutes.