Heat the oil in a wok, add the onion and cook for 5-7 minutes until softened. Add the ginger, garlic, lemongrass and 4 tbsp redcurry paste. Stir and cook for 2 more minutes.
Pour in the coconut milk, bring to the boil and simmer for 5 minutes. Add the salmon, broccoli florets. Cook for 5 minutes, stirring through lime juice and and basil. Serve with steamed rice.