Toss the CauliShoots with 1 tbsp of the olive oil and some seasoning. Spread out on a baking tray and put into the oven for 15 minutes.
Heat the rest of the oil in a large cast iron frying pan on a medium heat. Fry the red onions until soft. Add the cherry tomatoes and fry for five minutes until soft and bursting. Add the chopped tomatoes, seasoning and olives and cook for a final five minutes for the flavours to combine.
Meanwhile rub the cod fillets with the harissa paste and seasoning until well coated. Nestle them and the roasted CauliShoots into the tomato sauce and place into the oven. Cook for 15 minutes and serve.