heat ½ cup of olive oil in a large casserole. add 2 large chopped onions and cook very gently for about 30 minutes, until meltingly soft and pale. this method of reducing onions and olive oil to a thick, sweet puree is known as refogado, and is the basis for many portuguese dishes.
meanwhile, cut 1kg of skinned and filleted mixed fish into large chunks, salt and set aside for 20 minutes.
to the casserole dish, stir through 1 chopped clove of garlic and add 1 large chopped green pepper and cook gently for about 10 minutes until softened. add 1 tin (400g) of chopped tomatoes or 500g for fresh tomatoes, chopped, 2 teaspoons of paprika, 1 bay leaf, a few sprigs of fresh parsley and 1-2 small hot red chillies, whole. simmer for about 10 minutes until nicely reduced.
pour in 2 cups of fish stock, ½ cup of dry white wine and simmer briskly for 10 minutes.
add the prepared fish, 300g of cleaned prawns, 250g of closed, cleaned clams or mussels, cover and cook for 10 minutes until the fish is just cooked and the clams/mussels have opened. discard any unopened clams/mussels. check seasoning. dd a generous handful of fresh coriander leaves.
serve with chunks of crusty bread for dipping, or a few boiled potatoes.