Soak the wood ear mushrooms and glass noodles until soft, then finely chop and mix into the pork paste. Season with a little bouillon powder and black pepper. Peel the chayote, blend it, and strain to get about 6 1/3 cups (1.5 liters) of juice. Simmer the juice with the pork spare ribs, skimming off any foam as it boils.

Shape the pork paste mixture into small balls. Once the ribs are tender, drop the pork balls into the simmering broth. When the balls float to the surface, they are cooked. Season with 2 tablespoons fish sauce and 1 teaspoon vegetable bouillon powder. The chayote broth is naturally sweet, so you don't need to add sugar.

Place the rice noodles in bowls. Ladle the hot broth over the noodles, then top with ribs, pork balls, and fried pork sausage slices. Sprinkle with chopped cilantro, green onions, fried shallots, and black pepper. Enjoy a clear, naturally sweet broth with tender, flavorful pork balls.