Tip the rice into a bowl and cover with cold water. Whisk for 1-2 mins till the water goes cloudy. Drain the rice, rinse under cold water and tip into a small pan. Add 300ml boiling water and a pinch of salt. Cover. Bring to the boil.
When the water is boiling, turn the heat right down and gently cook for 25 mins till the rice is tender and has absorbed all the water. Take off the heat and leave to steam, lid on, for 5 mins to finish cooking. The rice will keep warm in the pan.
While the rice cooks, peel and finely chop the onion. Halve the pepper and scoop out the seeds. Roughly chop it. Peel and grate or crush the garlic. Halve the chilli, scrape out the seeds and white pith and finely chop the chilli. Grate or pare the zest from the lemon. Keep the lemon for later.
Warm 1 tsp olive oil in a deep frying pan or wok. Add the onion and red pepper. Season with salt and pepper. Stir and fry over a medium heat for 5 mins till the veg are soft and glossy. Add a splash of water if they start to stick. Add the garlic, lemon zest, 1 tsp dried oregano and the chilli. Stir and fry for 1 min.
Add the chopped tomatoes to the pan. Pour in 200ml boiling water. Pop on a lid. Simmer for 10 mins till the sauce has started to thicken. Stir every so often.
Carefully place the cod fillets in the tomato sauce. Cover. Simmer for 10-12 mins till the cod is opaque and cooked through – the flesh should flake when pressed with a fork.
While the cod cooks, roughly chop the parsley leaves. Serve the cod with the tomato sauce and rice, garnished with the parsley and with lemon wedges on the side for squeezing.