Gather all ingredients.
Place cubed pork in a medium bowl and season with soy sauce, salt, and sugar for marinade.
Add egg white and green onions and mix until well-combined. Cover and place in the refrigerator for at least 1 hour.
Heat 1 quart oil to 365 degrees F (185 degrees C) in a large, heavy saucepan or deep fryer. Coat pork with cornstarch.
Fry in hot oil until evenly browned, about 10 minutes. Drain on paper towels and set aside.
Heat oil for vegetables in a wok over medium heat. Stir in celery, bell pepper, and onion; cook until tender, about 5 minutes. Season with pinch of sugar and salt. Remove from heat and set aside.
Mix 1 cup water, 3/4 cup sugar, apple cider vinegar, ketchup, soy sauce, and salt in a large saucepan; bring to a boil over high heat.
Stir in cooked pork, celery mixture, and pineapple chunks with juice.
Return to a boil, then mix in remaining 1/4 cup water and cornstarch. Cook until thickened and warmed through, about 2 minutes.
