Heat the cooking oil in a casserole over a gas stove or fireplace.
Add red pepper and onion. Saute until onion is shiny and soft. Pour the coconut milk, and bring to a boil.
Add the halibut fillet, turn down the heat and let it simmer for 1 minute. Be careful so the fish doesn’t get too much heat.
Add 1 tablespoon of green curry paste, and stir carefully. Add the chopped spring onion.