In a medium bowl, mix the pork, cilantro, scallions (just the white and light green parts), water, fish sauce, sugar and pepper. Mix really well to fully incorporate all the ingredients. You can use a wooden spoon or, my favorite method, your hands.
One the ingredients are incorporated together, make the meatballs. This recipe usually yields about 20-25 meatballs depending on how big or small you make them. I like to make them on the smaller side because the cook quicker and are easier to eat. Roll a couple of tablespoons of the pork mixture between your palms, and place on a large sheet pan that you have oiled.
Once all the meatballs are formed, cover and refrigerate for 15 minutes. This gives the ingredients a chance to infuse the pork with all their amazing flavor.
While the meatballs are in the fridge, you can make the sauce. In a small bowl, whisk the lime juice, fish sauce, sugar and serrano together. Set aside. In another small bowl, add the grated carrots and 2 tablespoons of the lime juice sauce. Set aside.