Add the saffron threads to your hot chicken stock and set aside.
Cut the chorizo sausage into small chunks and place it in your cold paella pan. Turn the heat to medium and cook until it is nicely crisp.
Meanwhile cut the chicken into small chunks. Add it to the pan and stir well to coat in the paprikary oil from the chorizo. Cook for a couple of minutes turning regularly.
Remove the chorizo and chicken from the pan, but keep the oil in the pan.
Bring a kettle of water to the boil. Make a small cross in the bottom of each tomato, place them in a bowl and cover in boiling water.
Leave them to sit for 3 minutes then use a slotted spoon to remove them. Once they start to cool the skins should curl up and be easy to remove. Chop the tomato flesh into small dice and set aside.
Finely chop the onion, capsicum and garlic.
Add the olive oil to the chorizo oil in the paella pan and bring to the shimmer point. Turn the heat down to low and add the onion and capsicum. Cook for 3-4 minutes until softened and golden.
Add the garlic to the pan and cook for a couple of minutes until it is almost starting to sizzle. At this point add in the tomato, salt and pepper and stir well.
Pour in the stock, sprinkles over the smoked paprika and bring back to the boil. Stir in rice, ensuring you have a thin even layer. Bring everything to a simmer, then turn the heat to medium/low and cook for 15 minutes until stock has absorbed. Check the rice. It should be just cooked. If your stock evaporates before the rice is cooked add a little water to the pan.
Arrange the prawns over the top of the paella and sprinkle over the peas. Turn the heat up and continue to cook for 2-3 minutes until the prawns are just pink. During this time you should hear the rice on the bottom starting to crackle and smell the toasted rice smell.
Turn off the heat and cover the pan with a tea towel for 5 minutes before serving.