In a large bowl combine the pork and garlic and paste and shape it into small balls, around 1-inch in diameter.
Bring the stock to a boil, then add the pounded cilantro and garlic, and simmer for a few minutes to release the aroma. add the pork balls to the boiling stock and cook 3 minutes, or until the pork is cooked, skimming the surface for unwanted color and fat keeping the soup crystal clear.
reduce the heat and stir in the shrimp, followed by the sliced onion, mushrooms, noodles, scallion, fish sauce and sugar. continue simmering 1 minute more. then ladle into bowls and serve.