In a large pot place the water with the onions, garlic cloves, scallions, cumin, salt, pepper and the plantains. Cook over medium heat for about 5 minutes.
Reduce the heat to medium-low. Add the potatoes, yuca and pumpkin, and cook for about 10 minutes more.
Add the fish and cook for about 10 to 15 minutes more or until the vegetables are tender and the fish is cooked. Place all the vegetables and fish on individual plates except the broth, dividing the fish, and vegetables evenly.
Then top with hogao and serve with white rice and avocado on the side. Taste and adjust the seasoning. Serve the broth in small bowls and garnish with fresh cilantro.