Step 1Place the noodles in a bowl and cover with hot tap water. Let them soak until they are pliable and opaque, about 15 to 20 minutes. Drain and use kitchen scissors to cut them into 3- to 4-inch lengths.
Step 2To make the flavoring sauce, in a small bowl combine 1 1/4 teaspoons sugar, the fish sauce and water and stir to dissolve the sugar. Set aside.
Step 3In a wok or large skillet, heat the oil over medium-high heat. Add the garlic and stir-fry just until fragrant, about 15 seconds. Add the shrimp and pork and stir briefly to break up the meat. Sprinkle in the salt and remaining one-fourth teaspoon sugar. Keep stirring until the shrimp and pork have turned opaque, about 2 minutes. Stir in the Chinese chives. Because there is so much food in the pan now, use 2 cooking utensils to stir and toss the ingredients, ensuring even exposure to the heat. (Think of tossing a big salad.)
Step 4When the chives have collapsed by one-third of their original volume, after about 3 minutes, add the noodles and combine well. When all of the ingredients are well combined, give the flavoring sauce a stir and pour over the mixture. Continue stirring and tossing 2 to 3 minutes longer, or until the noodles and chives are soft and cooked.
Step 5Remove from the heat, squeeze 4 lime wedges (1 lime) over the noodles, and mix well to distribute the flavors. Transfer to a serving plate and serve immediately with the remaining lime wedges.