Place the pork chunks in a large bowl, add the beaten egg, soy sauce and salt and mix well, ensuring all the pork is coated in the egg mixture.
Tip the cornstarch into a seperate bowl then add the pork and stir to coat in cornstarch, shaking off any excess.
Fill a wok 2/3 full of oil and heat to 350 F. Fry the pork pieces in batches for about 2 to 3 minutes, or when they just start to get golden brown. Remove them from the oil and transfer to a sheet pan with a slotted spoon.
In a large saucepan over medium high heat, add 1 tbsp or oil, red bell pepper and onion. Sautee for 3-4 minutes until slightly tender but still crunchy.
Add the orange juice, white sugar, tomato paste, ketchup, vinegar and pineapple chunks. Bring to a boil, lower the heat and simmer for 5 minutes.
Slowly stir in the cornstarch slurry, stirring continuously, until you have the desired consistency. Add water to thin out the sauce if required. The sauce should be thick enough to coat the back of a spoon. Set aside.
Once you’re ready to combine everything, refry the pork in batches to crisp up the coating. Frying the pork twice prevents it from getting too soggy when added to the sauce.
Add the deep fried pork to the sauce and toss to coat. Serve with steamed rice and garnish with sliced scallions.