Portuguese halibut com piri-piri

For the piri-piri sauce, heat the oven to 220C/200C fan/gas 6. Wrap the two whole onions and both tomatoes individually in foil, put on a shallow baking tray and bake for 30 mins, then remove the tomatoes and continue to roast the onions for another 15-20 mins or until they are very soft when prodded. Unwrap the foil, then peel the onions and transfer to a blender jug with the tomatoes. Cover and leave to cool.

Heat the olive oil in small pan then scatter in the sliced onions, season with salt and sizzle gently over a low heat for 25 mins, stirring occasionally, until sticky and golden brown but not burnt. Tip in half the sticky onions with the roasted onions and tomatoes, and cover again and leave the other half in the pan to use later

Put a sturdy frying pan (cast iron is ideal) over a high heat and cook the whole chilies and garlic in the dry pan for 20 mins, turning them occasionally, until the garlic skin is burnt, the garlic is soft and the chillies are blistered all over. Slip the garlic cloves out of their skins, cut the stems off the chillies and tip both in the jug. Add all the remaining ingredients for the sauce, except the fish stock, into the jug. Season with a little pepper (white pepper if you have it) and very generously with sea salt, then blend until silky smooth. If you don’t have a blender then use a hand blender to combine everything in the container until very smooth. The sauce can be made two days ahead and chilled – you will only need a third of the sauce so you can freeze the remainder for another time.

Remove the fish from the fridge 30 mins before you want to cook it and brush the flesh, not the skin, all over with some of the sauce and season it with salt. Heat the oven to 180C/160C fan/gas 4. Heat the oil in an ovenproof frying pan and cook the fish, skin-side down, for 3-4 mins or until the skin is golden brown. Turn over the fish and add the butter, basting the fish as it melts, then roast the fish in the oven for 15-20 mins or until the fish flakes easily.

Put the remaining caramelised onions back over a low heat with 6 tbsp of the fish stock and simmer for 2 mins, then scatter in the broad beans and garlic, and cook for 2 mins, seasoning with pinches of salt, pepper and paprika, and set aside in the pan. Heat a third of the sauce in a pan with the 75ml of fish stock.

To assemble, spoon the broad beans down the middle of a warmed large platter or tray and spoon enough of sauce around the beans to cover the platter. Sit the cooked halibut on top, drizzle the melted butter over the top of the sauce, scatter over the parsley and a bit more paprika, then finish with a fine grating of lemon zest, if you like.