Put the saffron threads into a small pan over a medium heat with the sherry and warm them, not letting the pan come to a boil. Leave to cool. Heat the oil in a wide, heavy-based pan. Cook the spring onion for a few minutes.
Add the sliced garlic to the pan and cook for a minute or so more. Add the rice, slicking it in the oil, and then the prawns, sliced baby squid, pork and peas, and turn everything in the oil.
Heat the chicken stock, or make up the concentrate/cube with boiling water, and add the hot stock to the pan, followed by the warmed sherry and saffron. Stir to mix and bring back to a bubble, then turn down to the gentlest simmer but leave uncovered.
Cook without stirring for 15-20 minutes, by which time the rice should have absorbed the liquid and be tender.
Now you can fork the rice through to separate the grains, and check the seasoning, adding salt to taste.
Serve the paella edged with lemon wedges and sprinkled with coriander.
Recipe from Nigella: Kitchen by Nigella Lawson (published by Chatto & Windus).