For the fish stock
- 1kg/2lb 4oz fish bones, such as lemon sole, brill and plaice
- 1 onion, roughly chopped
- 1 fennel bulb, roughly chopped
- 100g/3½oz celery, sliced
- 100g/3½oz carrot, roughly chopped
- 25g/1oz button mushrooms, sliced
- 1 sprig fresh thyme
For the arroz verde
- 4 tbsp olive oil
- 60g/2¼oz shallots, finely chopped
- 12 garlic cloves, finely chopped
- 1 litre/1¾ pints fish stock (see above)
- 100g/3½oz finely chopped flatleaf parsley
- 1½ tsp salt
- 400g/14oz short-grain paella rice, such as calasparra
- 30 raw clams, preferably palourdes (vongole), scrubbed
- 200g/7oz raw small prawns, peeled
For the aioli
For the fish stock, put all the ingredients and 2½ litres/4½ pints water in a large pan and simmer gently for 30 minutes. Strain through a fine or muslin-lined sieve. If not using immediately, leave to cool, then refrigerate or freeze.
For the arroz verde, heat the oil in a 28–30cm/11–12in shallow flameproof casserole over medium heat. Add the shallots and fry for 5 minutes, or until soft. Add the garlic and fry for 40–60 seconds, then stir in the fish stock, parsley and salt and bring to the boil.
Sprinkle in the rice, stir once, then leave to simmer vigorously over medium–high heat for 6 minutes. Put the clams and prawns on top and shake the pan briefly so they sink into the rice a little. Lower the heat and simmer gently for 12 minutes. Almost all the liquid should be absorbed and the rice should be pitted with small holes. Discard any clams that do not open after cooking.
Meanwhile, for the aioli, mix the garlic and salt together to form a paste. Put in a food processor and add the yolk. Turn on the machine and very slowly trickle the oil through the hole in the lid until you have a thick emulsion.
Serve the arroz verde with the aioli.