Marinate pork and pork liver separately with light soy sauce and a little bit cornflour

Heat a wok add cooking oil, saute onion until translucent then put in pork. Cook until pork turn golden brown.Cook a while until pork is soft. Then add in carrot and potato. Season with oyster sauce and black pepper. Simmer it. When veges are halfway add pork liver and bell pepper. Cover and cook the liver, when it is done add the venigar. Don't mix it just cover and let it boil, then that is the time you mix.Cook for a minute. Then remove