1. Preheat the oven to 180°C/gas mark 4.
2. Heat 1 tablespoon of the oil in a medium saucepan set over a medium heat. Add the onion and cook for about 8 minutes, until softened, then add the garlic, oats, paprika and a pinch of salt and pepper and cook for 2 minutes more, stirring. Remove from the heat, then add the remaining 2 tablespoons of olive oil and the parsley and mix well.
3. Place the fish fillets on a baking tray. Spoon the oat mixture evenly over each fillet and roast in the oven for 20 minutes.
*Serve with sweet potato wedges and lemon wedges on the side.