To begin, rinse the rice under cold water until it runs clear. Cook the rice in lightly salted water until just underdone, about 80 percent cooked. Drain and set aside. Move on to preparing the seafood.
Clean all seafood components thoroughly. Pat dry and season with a pinch of salt and lime juice. Set aside for 10–15 minutes while you begin the sauté base.
In a wide pan or pot, heat the vegetable oil over medium heat. Sauté the onion, garlic, and bell pepper until softened and aromatic, about 5 minutes. Add the ají panca and ají amarillo pastes, stirring for 2–3 minutes. Proceed to deglaze.
Add grated tomato and white wine. Cook until the mixture thickens and the alcohol evaporates, about 3–4 minutes. Season with salt and pepper. This mixture will coat the rice and seafood later. Prepare to cook the seafood.
Add the mussels and fish stock to the pan. Cover and steam for 5 minutes until mussels open. Discard any that remain closed. Add shrimp, squid, and fish, and simmer gently for 3–4 minutes until just cooked. Transition to mixing in the rice.
Gently fold the partially cooked rice into the pan with the seafood. Add peas and sweetcorn. Stir carefully to prevent breaking the fish. Ensure the rice absorbs the juices and becomes fluffy. Proceed to finishing.
Sprinkle chopped coriander over the rice and add a squeeze of fresh lime juice. Taste and adjust seasoning as needed. Let the rice rest for 2 minutes with the lid on. Move to plating.
Plate the Arroz con Mariscos hot, garnished with extra coriander and lime wedges. Serve with ají sauce on the side if desired. Presentation tip: use a wide, shallow dish to showcase the seafood beautifully.