Heat the olive oil in a large, heavy casserole pot and add the garlic, sofrito paste, habanero pepper, Onion, celery, plantains, and the Potato and saute for 5 minutes over a medium heat, stirring, until the onions start to wilt.
Then add the cinnamon, Bijol, fillets, stock, water, and milk and stir gently to mix. Bring the mixture to a light boil, reduce the heat to a simmer, and simmer for 15 minutes, or until the fish flakes easily with a fork. Add sea salt and pepper to taste.
Serve the soup in warmed bowls and garnish with the chopped scallions.