Heat a large pan or wok over medium-high heat. Add 1 tbsp of vegetable oil and cook the green beans in batches, arranging them in a single layer. Cook each batch for 8–10 minutes, pressing down with a spatula until charred and cooked through. Repeat with the remaining beans and set aside.
In the same pan, heat the remaining 2 tbsp of oil over medium-high heat. Add the onion and cook for 5–6 minutes until softened. Add the ginger, garlic and chilli (if using) and cook for a further minute.
Add the marinated pork mince to the pan and cook for 7–8 minutes, stirring occasionally until the mince is well browned. Reduce the heat to medium and return the cooked green beans to the pan along with the dark soy sauce, All Purpose Stir Fry Sauce and a splash of water. Stir well and cook for 1–2 minutes until the sauce is thick and glossy. Add a little more water to loosen the sauce if needed, then serve immediately with steamed rice.
