Cut the pork into strips. Add starch and water in a bowl. Add the pork in the bowl and make each pork strip brush a layer of starch.

Mix the ketchup, sugar and rice vinegar in a bowl to make the sweet and sour sauce. ( Adjust the amount of material according to you perforce)

Heat a wok with enough oil, and fry the pork until slightly yellow, transfer it on a plate. Then fry it again until golden.

Heat a wok with the sweet and sour sauce, and stir the fried pork under middle heat for a few times. Transfer it on a plate and serve.