Make the Pork Balls: Place water chestnuts, scallions, pork, salt, soy sauce, and eggs in a large bowl. Mix with hands. Add bread crumbs and ginger and mix well. Chill mixture for 1 hour.
Shape into 1 inch balls and roll in cornstarch.
Heat 2 inches of oil to 370 degrees in a deep skillet or large pot. Carefully drop balls into oil one at a time, a dozen per batch. Fry the balls for about 1 to 2 minutes, or until they are golden brown. Break one open to make sure it is cooked through; there should be no pink left. Drain on paper towels. Reheat oil between batches.
Prepare the Sauce: Place pineapple juice, vinegar, soy sauce, sugar, broth, and ginger in a saucepan and bring to a boil. Mix cornstarch with water and, using a whisk, stir into the boiling mixture. Cook, stirring, for 3 minutes. Then reduce heat to very low.
Place pork balls in chafing dish and stir in enough sauce to coat.