Place cubed pork in a medium bowl, and season with 1 teaspoon salt, 1 teaspoon sugar, and 1 tablespoon soy sauce. Mix in the egg white and green onions. Cover, and place in the refrigerator at least 1 hour.
Heat 1 quart oil in a large, heavy saucepan or deep fryer.
Coat the pork with 1/2 cup cornstarch, and fry in the heated oil about 10 minutes, until evenly browned. Drain on paper towels.
Heat 1 tablespoon oil in a wok over medium heat. Stir in the celery, green bell pepper, and onion, and cook until tender. Season with salt and sugar. Remove from heat, and set aside.
In a large saucepan, mix 1 cup water, 1/4 teaspoon salt, 3/4 cup sugar, apple cider vinegar, ketchup, and 1 teaspoon soy sauce. Bring to a boil, and stir in the cooked pork, celery mixture, and the pineapple chunks with juice. Return to boil, and mix in 2 tablespoons cornstarch and 1/4 cup water to thicken. Cook until well blended.