Heat the butter in a medium pot over medium heat.
Add the onions, scallions and red bell pepper. Cook until everything is soft, about 5 minutes.
Add the rice, salt, and pepper and stir until well coated.
Add the vegetable broth, achiote, coconut milk, fish and ground cumin. Stir well.
Bring to a boil for about 5 minutes, then reduce the heat to low. Cover and cook for about 25 to 30 minutes or until the rice is just tender.
Taste and adjust the seasoning. Let it sit for about 5 minutes, add chopped scallions and serve.