Follow the steps in order for the best result.
In a large skillet or wok, heat a small amount of cooking oil over medium-high heat. Add the pork chunks and sear until beautifully browned on all sides, ensuring they develop a rich crust. Once browned, remove the pork from the pan and set aside, leaving any drippings in the skillet.
Carefully drain the liquid from the canned pineapple chunks into a separate bowl; this precious juice will form the base of our vibrant sweet and sour sauce.
In a medium mixing bowl, whisk together the brown sugar, soy sauce, cornstarch, and vinegar until completely smooth and the cornstarch is fully dissolved.
Pour this prepared mixture into the reserved pineapple juice, stirring well to combine all the sauce ingredients.
Return the browned pork to the skillet. Pour the combined sweet and sour sauce mixture over the pork. Bring the sauce to a gentle simmer, stirring continuously for several minutes, until the sauce thickens to a glossy, appetizing consistency that coats the pork beautifully.
Now, introduce the drained pineapple chunks, thinly sliced onions, and vibrant green bell pepper strips to the skillet, tossing gently to incorporate them with the pork and thickened sauce.
Continue to cook for approximately three minutes, allowing the vegetables to soften slightly while retaining a pleasant crisp-tender bite. Serve this enticing Sweet and Sour Pork immediately, spooned generously over a bed of fluffy steamed rice for a complete and satisfying meal.