Fish stock for paella

Method

1. To make the stock, heat the olive oil and cook the prawn heads, shells and fish head or bones for 1-2 minutes in a large saucepan (large enough for all the ingredients and 1.8 litres of water), breaking up the shells with a wooden spoon. Add the onion, fennel and spring onions and sweat over a medium heat for 10-15 minutes until they start to caramelise. Add the tomatoes, tomato purée and paprika and cook for 5 minutes more.
2. Pour the brandy into a ladle, light with a match and then immediately pour over the stock, allowing the alcohol to burn away. Deglaze the pan with a little hot water, scraping all the caramelised ingredients from the bottom with a wooden spoon, then add the thyme, bay leaves and 1.8 litres of water. Bring to the boil, then reduce the heat and simmer for 45 minutes to 1 hour, reducing the liquid to leave about 1.1 litres of stock.