First, char the bell pepper, corn, and tomatoes on an open flame. You can just put them directly on a gas element, or on the grill, until blackened and blistered.
When cool enough to handle, thinly slice the pepper, slice off the corn kernels, reserving any juices in the process, and dice the tomatoes. Reserve until needed.
Heat the oil in a large roasting pan. Sweat the onion and chorizo on medium heat until the onions are translucent and the chorizo is browned.
Add the garlic, paprika, turmeric, and fish sauce and fry until fragrant. Add the prepared vegetables and cook on high heat until the tomatoes lose their raw flavour, about 5-7 minutes.
Stir in the soaked rice and water, then season well. Cover and bring to the boil.
Meanwhile, preheat the oven or grill to 450 degrees F, with the rack placed in the lower third of the oven.
Once boiling, remove it from the heat, stir well, and arrange the frozen seafood on top. Do not stir once you add the seafood!
Cover and bake in the preheated oven or grill for 1 hour, or until the liquid has been completely soaked up by the rice. Turn off the heat and leave the paella in the oven to rest for a further 10 minutes, undisturbed so the juices can get soaked up by the rice.
Serve with a bit of chopped parsley and squeeze of lemon.