Heat the oil in a large, deep frying pan over a medium heat. Stir in the fennel and onion with a pinch of salt. Cook, for 15 mins, until softened. Stir in the chilli and half the garlic. Let it sizzle for 2 mins until fragrant, then stir in the tomato purée. Cook for 3-4 mins until caramelised before adding the chopped tomatoes and chickpeas, along with the liquid. Swill out the tomato cans with a splash of water and add this, too. Splash in some lemon juice and bring to a simmer. Cook for 20-25 mins, until the flavours have combined and the sauce has thickened. Season to taste, adding a pinch of sugar, if needed, and a splash more lemon juice. Stir in the prawns and cook for 2-3 mins until pink and cooked through.

Meanwhile, to make the gremolata, mix the remaining garlic with the lemon zest and parsley, then season with a pinch each of salt and pepper. Sprinkle the gremolata over the prawns. Serve in shallow bowls alongside some crusty bread, if you like.