Drizzle the salmon with lemon juice and season with salt and pepper. Heat 1.5 tablespoons of oil in a wok over medium-high heat and fry the salmon for 1 minute. Remove with a slotted spoon and set aside.
Pour the remaining 1.5 tablespoons of oil into the wok and heat over medium-high heat. Fry the ginger, onion, red chilli pepper, and Chinese cabbage for 2-3 minutes, stirring constantly.
Pour in the vegetable stock and coconut milk. Bring to a boil over medium-high heat, then reduce heat to medium and simmer for 1 minute.
Place the salmon pieces on top of the vegetables. Cover the wok and heat for 2 minutes until the salmon is heated through.