Prepare the conch by cleaning it thoroughly to remove any residual sand. Tenderize the meat by pounding it gently with a meat mallet to avoid toughness during cooking. Cut the conch into bite sized pieces and set aside.
In a large pot, heat the vegetable oil over medium heat. Sauté the onions, bell peppers, and garlic until fragrant and translucent, about 3–5 minutes. Add the achiote, cumin, salt, and black pepper, stirring to coat the aromatics in the spices.
Add the tenderized conch to the pot and sauté for another 2–3 minutes, allowing the flavours to meld. Pour in the coconut milk and water (or fish stock) and bring the mixture to a gentle simmer.
Add the plantain slices and potato cubes to the pot. Stir gently to ensure they are submerged in the liquid. Cover the pot and let the soup simmer on low heat for 20–25 minutes, or until the plantains and potatoes are tender.
Taste the broth and adjust the seasoning if needed. For added spice, carefully drop the whole hot pepper into the pot, ensuring it does not burst open unless you prefer a spicier flavour.
Squeeze the juice of two limes into the soup for a bright, tangy contrast to the creamy coconut broth. Stir in most of the chopped cilantro, reserving some for garnish.
Allow the soup to simmer for an additional 5 minutes, letting all the flavours blend beautifully. Remove the hot pepper (if used) before serving.
Ladle the soup into bowls, ensuring each serving has a mix of conch, plantains, and potatoes. Garnish with the reserved cilantro and serve hot with lime wedges on the side. Traditionally, this dish pairs beautifully with fresh corn tortillas or white rice.