This soup is meant to be the consistency of bisque, but if it becomes too thick, add a bit more of the reserved pork stock. I like the inexpensive but very succulent pork neck bones (look for those with lots of meat on them) for this, but this dish would work equally as well with country-style pork ribs, beef short ribs, or even oxtails. I always keep ground lemongrass (find it at Asian markets) on hand but feel free to use finely diced fresh lemongrass. The charm of this soup is its subtle, fragrant flavors, but if you like it spicy, serve hot sauce at the table.