Heat oil in a saute pan over medium heat. Add onion and saute for one minute. Reserve half of the green, red, and yellow peppers for garnish, and add the remaining ingredients to the onions. Cook for 15 minutes. Remove from heat and puree in a blender or food processor. Sauce can be cooled and used as needed.

Preheat oven to 350 degrees F.

Add the coriander to a dry saute pan over medium high heat. Keep the coriander moving in the pan or the product will burn. Toss for several minutes until a nutty smell comes from the pan. Immediately remove for the heat and allow to cool for a few minutes. Pulverize in a blender.

Peel and slice the plantain very thinly, dust with flour, and fry in vegetable oil until crispy. Remove from heat and drain on paper towel.

Saute remaining peppers for garnish.

Generously sprinkle toasted coriander on each of fish. Add olive oil to saute pan, when oil is hot sear each side of fish then finish cooking in a 350 degree F oven for 10 minutes. Pour excess oil from saute pan and add soffrito. Simmer and reduce to desired thickness. Remove pan from heat and stir in butter, constantly stirring until butter is incorporated.

Place fish on a platter or 2 serving plates and spoon sauce over half of the fish. Garnish with the Sauteed peppers, fresh cilantro, and crisp plantain chips.