2 gallons water, divided
3 pounds whole milk mozzarella curd (available at specialty Italian markets)
4 tablespoons salt, divided, plus more for serving
In a large pot, bring a gallon of water to a boil.
In a large bowl, break up the mozzarella curd into small pieces. Coat the curd with 2 tablespoons of salt, and set aside.
In another large bowl, salt the second gallon of water with the remaining salt and add as much ice as it can hold.
This is where it gets a little tricky. Carefully pour the boiling water over the salted curd. As the curds begin to melt, carefully stir with a wooden spoon for 1 minute. Submerge both of your hands in the ice water for as long as you can stand it, because you're about to stretch the mozzarella in boiling hot water. The curd will have settled into the bottom of the bowl, and at this point you have to work quickly or risk over-cooking the curd.
Dip your hands into the hot water and begin stretching the mozzarella. By stretching the cheese you insure that all the curds have completely melted. The curds will become incredibly soft and have buttery shine, and also, it smells wonderful. Form the mozzarella into tomato size balls, and then drop the mozzarella into the ice water to stop the cooking process. Work quickly, as the mozzarella will start to become rubbery the longer it sits in the hot water.
Wrap each mozzarella ball tightly in plastic wrap and store in the refrigerator for up to a week.