I. Add the onions, garlic, bay leaves, oregano, salt, pepper, and oil to a large heavy pot or Dutch oven over medium heat. Cook 5 minutes or until the onions are soft. Stir in the celery, bell pepper, and tomato paste, and continue to cook for 1 minute . II. Pour in the wine, and bring the ingredients to a boil for 5-6 minutes or until the liquid is reduced by half.
III. Reduce the heat to medium, and stir in the tomatoes, clam juice, broth, and sugar. Cover and simmer 30 minutes. Taste the broth; add salt and pepper as needed. IV. Add the clams and mussels. Cook only until the shells open, and immediately transfer the opened calms and mussels to a separate bowl. Toss out any shellfish that won't open.
V. Lightly season the fish, shrimp, and scallops with salt and pepper. Add them to the stew, and simmer covered 3 minutes or just until the shrimp turn opaque. Note: If the shrimp turn opaque before the fish is done, remove them from the stew to prevent them from overcooking. VI. Turn off the heat, discard the bay leaves, and return all of the ingredients back to the stew. Divide the stew into bowl, garnish with fresh basil, if desired, and serve warm with crust bread.