Method 1: cooking the fish and sauce separately
- Heat oven to 180℃/fan 160℃. Heat the olive oil in a medium saucepan over medium-low heat. Add the onion, carrot, celery and garlic and season with sea salt and some freshly-ground black pepper. Cook, stirring occasionally, until very soft, 15 to 20 minutes; you want the veg to cook gently without taking on any colour.
- Meanwhile, line a baking tray with foil. Arrange the cod fillets in a single layer, drizzle with extra virgin-olive oil and season with sea salt, freshly-ground black pepper and your seasoning of choice (I used dried parsley, basil and oregano). Bake until just opaque and easily flaked with a fork, 10 to 15 minutes depending on the size of the fillets.
- Back to the sauce. Turn the heat up to medium-high. Add the halved tomatoes and cook, stirring occasionally, until they soften and release their juices, around 5 minutes. Add the peppers and water, season with sea salt and bring to a simmer.
- Simmer covered, with the lid slightly ajar, for 4 minutes then simmer uncovered for another 4 minutes. Remove the saucepan from the heat; tear and stir in the fresh basil. Taste and season with extra sea salt and freshly-ground pepper, if necessary.
- To serve, arrange the fillets on a platter and top with the tomato and red pepper sauce.
Method 2: baking the fish in the sauce
- Follow the instructions until step 4 (step 4 inclusive). Taste and season the un-simmered sauce with sea salt and freshly-ground black pepper then transfer it to a baking dish.
- Season the cod fillets with sea salt, freshly-ground black pepper and your seasoning of choice (I used dried parsley, basil and oregano). Nestle the cod fillets into the sauce. Bake until the cod is cooked (opaque and easily flaked with a fork), 10 to 15 minutes.