1: A day ahead, place the chickpeas in a large bowl with water to cover and leave to soak overnight.
2: The next day, drain the chickpeas and place them in a saucepan with fresh water to cover. Bring to the boil, skimming the surface as necessary. Reduce the heat to very low and leave them to simmer, uncovered, for 2 hours, or until the chickpeas are tender. Remove the pan from the heat and leave the chickpeas to cool in the water in the uncovered pan. They will expand in size.
3: Meanwhile, mix together the sea salt flakes and saffron. Place of piece of clingfilm large enough to wrap around the pollock on the work surface. Sprinkle half the salt mix on to the clingfilm and place the pollock on top, then sprinkle the remaining salt mix over the fish and wrap in the clingfilm tightly. Place this parcel into the fridge for 1½ hours.
4: Heat the olive oil in a large flameproof casserole over a medium heat. Add garlic, red chillies and onions and fry, stirring occasionally, for 6–8 minutes until the onion has softened.
5: Add the chorizo to the pot and continue frying for a further 5 minutes so the red paprika-soaked oil comes out from the sausage. Stir in the bay leaves, cinnamon stick, cumin and paprika and fry, stirring, for a further 3–4 minutes.
6: Preheat the oven to 170°C/Gas Mark 3. Drain the chickpeas and add them to the pot, then add the canned tomatoes and pour in the stock. Bring to the boil and put it in the oven for 45 minutes. Remove the pan from the oven and taste the chickpeas. The sauce should have reduced a little and thickened. Add salt, if necessary.
7: Rinse the pollock thoroughly in running cold water. Pat it dry and place on top of the chickpeas. Place the pot back into the oven for a further 15 minutes, or until the fish is cooked through and the flesh flakes easily. Remove the pot from the oven. Gently take the fish from the pot and place it onto a large serving plate. Stir the spinach into the hot chickpeas until it just wilts. Spoon this mix over and around the fish and serve immediately. Remember to take out the bay leaves and the cinnamon.