To make cilantro paste, puree first six ingredients in a mortar and pestle, or blender, until a fine paste is formed. You can also do this by hand by first chopping all ingredients, except fish sauce, together on a board to form a paste. Then mix with fish sauce in a small bowl. Set aside.
Follow directions on packages for reconstituting cellophane noodles and dried mushrooms, if necessary. Noodles usually need to soak in warm water for about 15 minutes; mushrooms about 30 minutes.
While ingredients are soaking, make dumplings by combining ground pork, fish sauce, garlic, and cornstarch in a bowl. With your hands, form small meatballs, about the size of hazelnuts. Set aside.
When noodles and mushrooms are finished soaking, drain. Remove and discard the tough stems and slice mushrooms into julienne strips. Cut noodles into 2 by 3 inch lengths.
Place all ingredients near stove and bring chicken stock to a boil in a large stockpot. Reduce heat to a simmer and add pork balls, mushrooms, and noodles. Cook, uncovered, until pork is done, about 10 minutes. Stir in paste and adjust seasonings with pepper and fish sauce. Ladle into serving bowls, sprinkle with sliced scallions and cilantro leaves, and serve immediately.
c.1997, M.S. Milliken & S. Feniger, all rights reserved