Heat a paella pan until hot and add half the oil. Add the chorizo and cook for 3 minutes until the fat is rendered and it is slightly browned. Transfer to a plate and set aside.
Add half the garlic and cook for 1 minute. Add the smoked paprika and cook for 20 seconds. Now add the prawns, season and cook them for 3 minutes. Set aside. The prawns must not be cooked through. Transfer to the same plate as the chorizo and cover to keep warm.
In the same paella pan, add the remaining oil and sauté the onion for 2 minutes. Add the remaining garlic and the diced red pepper and cook for 2 minutes.
Stir in the tomato paste until the pan ingredients are mixed well. Now stir in the tomato purée and fish stock. Bring to the boil and season. Simmer for 5 minutes.
Sprinkle the rice over the simmering stock, cover and reduce the heat to medium low. Leave to cook uninterrupted for 20 minutes over low to medium heat. Do not stir the pan until the rice is cooked.
Add the mussels and cook for 5 minutes.
The chorizo and half-cooked prawns can now join the rest of the ingredients in the pan. Continue cooking for another 5 minutes. This allows the seafood to steam nicely.
Remove from heat. Sprinkle with parsley and serve with lemon wedges. Buen provecho!