Cut the pork into bite-sized pieces.
In a medium dish, mix the cornstarch, salt, and pepper for the batter.
In another medium dish, lightly beat the egg.
Set up an assembly line and coat the pieces of pork in the egg and then dredge it through the cornstarch mixture.
In a large pan on medium-high heat, add the oil for frying the meat.
When the oil is hot and shimmering, add the coated pork to the pan separated enough so you can turn them to cook on all sides. Cook for about 2 minutes per side or until each side is a deep golden brown.
Once the pork is fully cooked, remove to a plate.
With a small grater, grate the chunk of fresh ginger into the pan.
Grate in the garlic, or mince the garlic and add to the pan.
Cook until fragrant (about 1 minute)
Add the onion, pepper, and tomato. Cook until tender.
In a small bowl, mix the sauce ingredients.
Add in the sauce. Bring to a simmer.
Stir vegetables and sauce until the mixture has thickened.
Add in the pineapple.
Finally, add back in the pork.
Stir to coat and reheat the pork.
Serve hot with your favourite side.