Christmas Eve fish broth with multiple seafood varieties follows Italian holiday fasting traditions. This high protein mediterranean soup is a family Vigilia ritual.
In a large heavy pot, heat the olive oil over medium heat. Add onion, celery, and carrot. Sauté for 5–7 minutes until softened, stirring occasionally for even cooking.
Add the minced garlic and sauté another minute until fragrant. Stir in the oregano and crushed red pepper flakes; cook 30 seconds to bloom aromas.
Pour in the white wine and simmer for 2–3 minutes, scraping any fond, until reduced by about half.
Add the crushed tomatoes and fish stock. Bring to a gentle boil, then reduce heat to low, cover, and simmer for 25 minutes. Skim off any foam for a clear broth.
Raise heat to medium-low and add clams and mussels. Cover and cook 4–5 minutes until they open. Immediately remove any that do not open.
Add the shrimp, scallops, squid, and fish fillets. Simmer gently for 4–6 minutes, being careful not to overcook; seafood should just turn opaque.
Taste and adjust seasoning with salt and pepper. Ladle the soup into bowls, sprinkle with chopped parsley, and serve hot with crusty bread if desired.