This is a Filipino meta-recipe.
You can have Sinigang na X where X can be a large variety of different kinds of meats and seafood. The three classic versions for the X would be pork, chicken and bangus respectively.
A word about bangus (milkfish). It's a fish that was traditionally found in the sea but can grow in brackish water. It's one of the older examples of aquaculture — at least 800 years old in the Philippines. The fish are bony — very bony and it's a skill to eat them.
Sinigang is a sour clear broth with one or more sources of meat and/or seafood, a ton of vegetables, and one souring agent. There is a purity of flavor coming from one very clear-cut souring source which neatly dovetails into the umami of the broth from the meat/seafood.
It is traditionally eaten with rice. The rice is frequently topped with fried garlic and/or fresh scallions but these are all details.
There are traditional recipes but there are clearly two dimensions to the dish — what meat/seafood you choose and what souring agent you choose.
Filipinos love sour food. This is a necessity forced by a tropical climate and a few millennia of no refrigeration turned into a cultural trait. It's one of the few ways to preserve food in a tropical climate so that there is no wastage. There is a difference though. The souring agents are cooked through. It gives them a "rounded mellow" flavor rather than the aggressive hit of acidity that you would get without cooking. There has to be enough sourness to wake up the taste buds but not so much as to make it pucker and inedible.
The list of souring agents is endless — vinegar made from all sorts of sources (coconut, palm, sugarcane, pineapples, etc.), tamarind, calamansi, kamias, santol, green mangoes, green guava, star fruit, green pineapples, even leaves of various plants, etc. This list barely even scratches the surface of this subject. The Philippines probably has the longest list of souring agents of any culture that the CC knows about.
Needless to say the souring agents are not substitutable for each other. It does matter whether you are making a sinigang with a hearty ingredient like pork or delicate ones like seafood. Santol which has an astringent tannic component would be most inappropriate for a seafood sinigang while almost all delicate fruit-based versions would work wonderfully.
There are also some classic touches about the choices of vegetables in a sinigang — a starchy root (taro, banana hearts or "New World" potatoes), some "green protein" typically long beans, and some greens in many many different forms — everything from sili (chili leaves) to bok choy, kang kong, and malunggay. Needless to say once tomatoes were discovered and transferred to the "Old World", they became irresistible additions for reasons we have covered on the blog before.
The ingredients are rotated with the combinatorial game that we have talked about extensively on the blog — you will see corn, carrots, radishes, eggplants and all kinds of other vegetables in there. There's a pairing bias though. You see lighter vegetables with seafood and more aggressive ones like eggplants with meat which makes logical sense based upon the palate profile.
Make no mistake though. The star is the sour broth.
One last word about the use of Filipino-style fish sauce called patis. It's basically the same concept as the Roman garum or the Thai nahm pla but it's arguably different. The CC would have no trouble distinguishing it in a blind tasting. You could substitute but it won't be the same.
Just like in Thai recipes, you don't add salt to the dish. The salt comes via the addition of the patis. Additionally, for this recipe with clams, they will give off plenty of salty liquid. Traditionally, the patis is always added towards the end where you can control the level of saltiness. (It also adds substantial umami to the dish.)
This makes a perfectly good soup even in the absence of rice which is heresy as far as the Filipino world is concerned but the CC can live with that.
After all this long explanatory buildup, this is not a difficult recipe. It's what Filipino moms make when they are too lazy to make something. It's really so simple as to defy its excellence.
Sinigang na halaan
1 large onion (sliced)
1" ginger (chopped thinly)
2 pieces ginger (chopped thinly)
1 chili (sliced lengthwise - optional)
2 small tomatoes (chopped into large pieces)
2 cups tamarind water (read below)
2 cups water
1 lotus root (cut into 1/3" slices)
2 cups long beans (sliced into 2" pieces)
4 pieces baby bok choy (tough bottom parts cut off)
2 sprigs chili leaves (sili leaves)
patis (to taste)
Note: Various markets (Filipino, Indian, Thai) carry frozen "green fruits" and both fresh and dried tamarind. They are perfectly excellent in making the various sour broths because the textural component is not important in the least.
First make the tamarind water. Heat up 2 1/2 cups of water with tamarind pods and bring to a boil. Simmer for 10 minutes. Let it sit in the cooling water. When it has cooled down, separate the water from the pods using a strainer. Discard the solids. Retain the tamarind water.
Heat up the oil in a sturdy pot. Add the onions, ginger, garlic and chili (if using) and fry for a bit till soft. Roughly 6 minutes.
Add the tamarind water, the water and bring to a boil. Add the lotus roots and let cook for 3 minutes. Add the long beans and let cook for 4 minutes.
Add the clams. Let them cook till they open. Roughly 8 minutes.
Turn off the heat.
At the very end, add the tomatoes, the bok choy and the chili leaves and let them sit for a few minutes to wilt. Add the patis to taste.
Serve immediately with rice (or not.)