Briefly marinade fish with chopped garlic, lime juice and salt & pepper. Set aside.
In a large saucepan, heat olive oil over medium heat. Cook chopped onions until softened.
Stir in chilli flakes, paprika, and season with generous amount of salt & pepper.
Add in chopped tomatoes and chilli powder. Bring to boil and let cook until slightly reduced. Stir in half the coriander leaves. Remove half of the tomato mixture from the pan, set aside.
Layer the marinated fish fillets into the pan, pouring in the marinade altogether as well. Top off the fish fillets with the remaining tomato mixture.
Pour in coconut milk. Reduce heat and cover, let simmer for 15 minutes.
Taste & adjust seasonings (more salt probably). Garnish with remaining coriander leaves. Serve hot with rice or crusty bread.