Heat the oil in a large saucepan and cook the onion and garlic over a medium heat for 3-4 minutes without browning.
Add the Chorizo sausage and cook for a further 2-3 minutes.
Stir in the red pepper and the rice until everything is evenly mixed and the rice is translucent (1-2 minutes).
Add the stock, tomato puree and season with salt and pepper. Cover the pan and cook over a medium heat for 10 minutes.
Add the prawns, Mussels and the peas. Stir well.
Leave the pan uncovered and cook for a further 8-10 minutes stirring from time to time until the rice is just cooked.
Remove the pan from the heat, cover with a clean tea towel and leave to stand for 5 minutes. Taste and add more seasoning if necessary.
Garnish with chopped fresh parsley and serve.