In a large pot, heat the vegetable oil over medium heat.
Add the chopped onion and minced garlic, and sauté until the onion is translucent.
Add the chopped tomato and bell pepper, and cook for another 5 minutes until the vegetables are soft.
Pour in the fish or vegetable broth and coconut milk. Add the dried thyme, ground black pepper, and salt to taste.
Bring the mixture to a boil, then reduce the heat and let it simmer for about 10 minutes.
Add the fish pieces to the pot and simmer for another 15-20 minutes, or until the fish is cooked through and tender.
Garnish the soup with freshly chopped cilantro.
In a large pot, bring salted water to a boil. Add the green and ripe plantain chunks and cook until they are tender, about 20-25 minutes.
Drain the plantains and transfer them to a large mixing bowl.
Add the coconut milk, butter, and salt to the plantains. Mash the mixture until it is smooth and well combined. You can use a potato masher or an electric mixer for this.
Enjoy your meal!