Season the pork pieces with 1 tbsp soy sauce and coat with 1 tbsp cornstarch.
Heat oil in a frying pan over medium-high heat and fry the pork until golden brown. Remove and set aside.
In the same pan, stir fry the bell peppers, pineapple, and carrot until tender but still crisp.
In a small bowl, mix vinegar, sugar, ketchup, and the additional soy sauce to create the sauce.
Add the sauce to the vegetables in the pan and bring to a boil.
Mix 1 tbsp cornstarch with 2 tbsp water and add to the pan to thicken the sauce.
Return the pork to the pan and stir to coat with the sauce evenly.
Serve hot with steamed rice.