Boil some salted water in a pot, remove from heat and add in the prawns. Return to low heat, and as soon as it comes to boil, turn off the heat again. Let it sit until needed (you will use the prawn ‘stock’ later).
Fry diced green pepper, tomato and onion in a paella pan (or any flat, wide pan) with some olive oil. Add sliced calamari, and cook for 10 minutes. This is the sofrito.
Add the uncooked rice into the sofrito and add ½ cup olive oil. Add the chopped chorizo, sliced chicken breast and 3 cups of water from the prawn pot. Add paprika and saffron.
Stir and set over low heat for 20 minutes. As the water soaks into the rice and reduces, continue adding water from the prawn pot until rice is cooked and all the water has evaporated.
Mash salt, parsley and garlic together in a mortar and pestle or food processor until you make a rough paste. Add and stir through the rice, add a little more water if needed and the prawns. Cover and set aside for 5 minutes. Serve topped with slices of lemon to squeeze over.