Preheat the oven to Gas Mark 4, 180°C (350°F).
Place the peppers, courgette and garlic in a roasting tin. Add 1 tablespoon of oil, sprinkle over the cumin, season and toss to combine. Roast in the hot oven for 15 minutes. Remove from the oven and add the tomatoes. Return to the oven for a further 5 minutes. Then place fish fillets on top of the vegetables, drizzle over the remaining oil, season and roast for approximately 15 minutes until the fish is cooked through.
To make the Basil oil: Simply place the basil leaves in a mortar with a little salt and the olive oil and stir with the pestle until the leaves break down. Alternatively use a mini processor.
To serve: Drizzle a little basil oil over the hake and serve with the roasted vegetables and boiled potatoes.