Heat the olive oil in a large pot over medium heat. Add the diced onion and red bell pepper and cook until the onion turns soft, about 5 minutes.
Stir in the minced garlic and jerk seasoning. Cook for 1 minute until the garlic is fragrant.
Add the diced tomatoes, fish broth, and thyme. Bring the mixture to a simmer and cook for 10 minutes to let the flavors blend.
Add the sliced plantains to the pot. Simmer for 8 minutes until the plantains begin to soften.
Gently place the snapper pieces into the broth. Season with salt and black pepper. Simmer for 5 to 7 minutes until the fish flakes easily.
Remove the pot from the heat. Sprinkle with chopped cilantro before serving.