This is a soup similar to what my mom used to make us when we were kids and she was still cooking. Basic but good and easy to make. I am posting this for my dear friend Pris, a blossoming cook in every sense of the word.
I am not too fond of eating boiled pork, so unless I'm making Bah Kut Teh, I do not expressly seek to use pork ribs for soup. What I normally do is buy pork for steak that comes with some bone, use the pork for making dishes like Pork with Ginger and Chives, Sweet and Sour Pork etc and then use the leftover (uncooked) bones for soup.
There are different ways of making basic stock and it all depends on what you prefer. As a rule, if you bring to a boil pork in cold water you'll get a cleaner soup and meat simply because all the impurities would come out in force and you'd be obliged more or less to rinse the meat and cook it in a new batch of water.
Or you could first bring water to a boil in a pot and then add in the meat. And once it comes to a boil again, lower the heat and let the soup simmer gently for a few hours for too much boiling will harden the meat. The impurities will still come out, but much reduced and easily skimmed off from the soup as you cook it.
Or like me for this basic soup, you could fry some ginger and garlic in a little sesame oil till fragrant, add in the pork meat/bones to seal in the juices before adding in boiling water (from a kettle for example). And then you let the soup simmer, adding in the vegetables e.g. shredded zucchini, carrots, leek, celery, spinach etc only about 15 minutes before serving. Cabbage is best blanched once or twice (for better digestion) before being added to the soup and if you intend to keep the stock and re-use it the next day, then it's best not to add the cabbage into the main stock or it'll turn sour later on. Stock is anyway best a day old and you could also clean it better the next day once the fat has hardened on the surface of the soup.
Add salt and pepper to taste, of course. Fresh coriander leaves make a nice addition too.
And with this you can make a soup with fishballs etc, use it as stock for steamboat, sauces or make rice porridge with it.
You folks out there, if you have other tricks, do share, it would be interesting to learn of better ways of making yummy soup.