In a bowl; mix the ground pork with the sesame oil until well mixed, then mix in the cornstarch, egg and soy sauce.
Prior to shaping the meatballs, have a plate ready to set your meatballs inches Wet your hands under cold water. Take small portions of the meat mixture, about the size of walnuts, and roll them in-between your palms, shaping them into balls. Keep wetting your hands as to prevent the meat from sticking to your hands. This will also help in producing an even, smooth surface. Once all meatballs have been shaped and placed in plate; set aside.
Preparing Sweet and Sour Sauce:.
In a bowl; blend the cornstarch with the water. Add the sherry, soy sauce, tomato paste, sugar, and vinegar. Drain the liquid from the pineapple and add liquid to the sauce mixture. Set the pineapple chunks aside.
Heat the 3 tablespoons of oil in a wok or skillet and fry the meatballs until evenly browned and cooked through. Remove them from pan using a draining-spoon and place on a paper-towel lined plate.
To the hot wok or skillet add more oil if necessary. To the hot oil, add the onion, peppers and carrots. Stir fry for about 5 - 9 minutes until slightly softened.
Give the sauce mixture a stir; pour it into the pan and bring to a boil, stirring all the time. Stir in the meatballs and pineapple chunks and cook, stirring over reduced heat for about 3-5 minutes. Serve hot with rice.
NOTE: When I have brought this to different events I've transferred the completed cooked recipe into a crock pot to keep it warm for a potluck service. These have always disappeared.