Clean the tanigue by removing the gills and internal organs, divide the fish by slicing into 4 pcs each.
Wash in running water to clean the blood from the fish and set aside.
Boil the tamarind in 2 cups of water until tender. Cool. Then strain the tamarind and press it in the strainer to extract the juice in a bowl. Set aside.
In a pot, heat oil and saute garlic, onion, ginger for a few minutes then add the tomatoes and saute again for a few minutes or until the tomatoes are soft.
Add the miso and stir cook for a few minutes also then pour the water, tamarind juice and bring to a boil.
Boil for at least 5 minutes then add the green chili and season with patis and Magic Sarap.
After a minute or two, put the tanigue in boiling broth one by one then continue boiling for 2 minutes.
Then add in the mustard leaves and simmer for 1 minute then serve hot.