Heat a large saucepan or wok over medium-high heat and add coconut oil.
Sauté onions until soft and translucent.
Add red pepper and spice paste, and stir-fry until sizzling and fragrant.
Pour in coconut milk, stock, and add lime leaves. Bring to a boil, then reduce the heat and simmer gently, uncovered for 5 minutes.
Add the salmon and simmer for about 5 minutes or until the fish is cooked.