1, Using your fingers, strip off the leaves and snap off the tender tops of each chrysanthemum stem. Discard the stems along with any discolored leaves and small buds. There should be about 3 cups packed leaves. Rinse the leaves well to remove any grit and drain in a colander. Cut the leaves into 1-inch pieces and set aside.
2, In a 3- or 4-quart saucepan, heat the oil over medium heat. Add the onion and cook gently, stirring occasionally, for about 4 minutes, or until fragrant and soft. Add the water and salt, raise the heat to high, and bring to a boil. Lower the heat to a simmer. Use 2 teaspoons or demitasse spoons to shape the dumplings. Scoop up a smallish mound of the paste with 1 spoon. (The dumplings nearly double in size, so you don’t want to start with a huge spoonful of paste.) Pass the mound back and forth from 1 spoon to the other, forming it into a relatively smooth round or football shape. When you’re satisfied, use the second spoon to push the dumpling gently off the spoon into the simmering broth.
3, After the dumplings float to the surface of the broth, let them simmer, uncovered, for 10 to 12 minutes, or until cooked through. Taste and season with up to 1 tablespoon fish sauce; how much you use depends on the saltiness of the meat paste. If you are not serving the soup right away, turn off the heat and cover.
4, Just before serving, return the soup to a simmer and add the chrysanthemum leaves. When they wilt and turn deep green, after about 1 minute, turn off the heat. Taste and add extra salt or fish sauce, if necessary. Ladle into a serving bowl and sprinkle with lots of black pepper. Serve immediately.