Heat olive oil in a 14- to 15-inch paella pan over medium heat. Add onion, garlic, and pepper; cook and stir for a few minutes. Add chorizo sausage, diced chicken, and rice; cook for 2 to 3 minutes. Stir in 3 ½ cups stock, wine, thyme leaves, and saffron. Season with salt and pepper. Bring to the boil, and simmer for 15 minutes; stir occasionally.

Taste the rice, and check to see if it is cooked. If the rice is uncooked, stir in ½ cup more stock. Continue cooking, stirring occasionally. Stir in additional stock if necessary: use up to 2 cups additional stock, 5 cups total. Cook until rice is done.

Stir in squid, tomatoes, and peas. Cook for 2 minutes. Arrange prawns and mussels on top. Cover with foil, and leave for 3 to 5 minutes.

Remove the foil, and scatter parsley over the food. Serve in paella pan, garnished with lemon wedges.