Note: You can use plain water to make this soup. But if you feel like using broth, keep in mind that the basic stock that is used in modern Thai cuisine is most commonly made with pork bones or chicken carcasses and not much else. If you use the kind of stock that is made with added onions, carrots, celery, tomato paste, etc., it will drastically change the flavor and appearance of this soup. I use plain water; the flavor of the pork and seasoning paste in it as well as the soy sauce and fish sauce which you add later are enough to turn it into a flavorful broth even within such short cooking time