This version is from Fay Maschler’s ” Eating In”. The original sweet and sour sauce originated in Hunnan, China and was a light vinegar and sugar mixture with little resemblance to the dish served in many Chinese restaurants today.
Chop the pork into 1 inch cubes and put in a bowl with the soy sauce and garlic. Turn with your hands to coat.
Meanwhile mix together the sauce ingredients, stirring the liquids and then the sugar and sauces into the potato flour.
Add the beaten egg to the pork and stir again.
Heat the oil in a wok to a depth that will cover the meat. Roll each meat cube in cornflour and assemble on a plate.
When the oil is chip frying hot add the meat and cook until the outside is crisp and lightly browned. Remove and drain on kitchen paper.
Fry the onion in a little fresh oil in a smaller pan. Add the sauce mixture and bring to a simmer- it will thicken and shine.
Repeat the meat frying for a minute or two then drain on kitchen paper again.
Serve the meat on some boiled rice with some of the sauce trickled over and the rest served separately for those who want more.