Heat the sesame oil in a large wok over a high heat. Salt and pepper the pork then add to the wok and cook until it's brown and caramelised on all sides. Remove from the wok and place in a bowl. Add the ginger, garlic and onion and cook for 5 minutes.
Mix the chicken stock, soy sauce, rice vinegar, chilli flakes, sugar and cornflour. Add to the skillet and bring to the boil. Simmer for a few minutes then return the pork to the wok along with the red pepper and pak choi. Cook for a couple more minutes until the pak choi has wilted then add the rice and stir through. Serve topped with chopped coriander, peanuts and a squeeze of lime.