Heat the vegetable oil in a large pot over medium heat. Add the chopped onion, red bell pepper, and minced garlic. Sauté for 3-4 minutes until fragrant and softened. Stir in the achiote powder, ground cumin, and oregano, cooking for an additional minute to bloom the spices.

Pour the fish or seafood stock into the pot, stirring to combine with the sautéed vegetables and spices. Bring the mixture to a gentle boil, then reduce the heat to medium low. Stir in the coconut milk, ensuring it blends smoothly with the broth.

Add the sliced plantains, cubed potatoes, and corn pieces to the broth. Cover the pot and let the vegetables simmer for 15-20 minutes, or until they are tender but not falling apart.

While the vegetables cook, season the shrimp, mussels (or clams), and fish fillet pieces with salt and black pepper. Set them aside to allow the seasoning to penetrate.

Once the vegetables are nearly done, gently add the seasoned seafood to the pot. Start with the fish chunks, followed by the shrimp and mussels. Cover the pot and simmer for 5-7 minutes, or until the seafood is cooked through. The mussels or clams should open during this process; discard any that remain closed.

Taste the broth and adjust seasoning as needed with additional salt or a squeeze of lime juice for brightness.

To ensure an authentic touch, garnish the soup with freshly chopped cilantro. If desired, serve with steamed white rice or warm tortillas on the side for dipping and balancing the rich flavours.

For an elegant presentation, ladle the soup into deep bowls, ensuring a mix of vegetables and seafood in each serving. Place a wedge of lime on the side and encourage diners to squeeze it over their soup for an extra layer of flavour.

Enjoy the soup while hot, savouring the creamy, aromatic coconut broth that blends harmoniously with the delicate seafood. This dish pairs beautifully with a refreshing drink, such as fresh tamarind juice or agua de horchata.