Heat olive oil in a large Dutch oven over medium-low heat. Add diced onion, minced garlic, and sliced fennel if using. Cook 5-7 minutes, stirring occasionally, until onion is translucent and garlic is fragrant but not browned.
1 large onion, 6 cloves garlic, 1 bulb fennel, 0.25 cup olive oil
Pour in white wine and scrape up browned bits from the bottom of the pot. Simmer 3 minutes until wine reduces by half. Add crushed tomatoes, fish stock, bay leaf, and red pepper flakes. Bring to a gentle simmer.
28 oz crushed tomatoes, 1 cup dry white wine, 2 cups fish stock or clam juice, 0.5 tsp red pepper flakes, 1 leaf bay leaf
Reduce heat to medium-low and simmer uncovered for 15-20 minutes, stirring occasionally, until broth thickens slightly and deepens in color. Taste and adjust salt carefully due to clam juice saltiness.
Add fish chunks first, nestling into the broth. After 2 minutes, add shrimp. After another minute, add clams and mussels. Cover pot and cook 3-5 minutes until shellfish open and shrimp turn opaque. Discard any shellfish that remain closed.
1 lb clams, 1 lb mussels, 1 lb large shrimp, 1 lb firm white fish
Remove pot from heat immediately when seafood is done. Stir in chopped parsley and torn basil. Let sit 2 minutes to infuse herbs into broth. Serve immediately with crusty bread.
0.5 cup fresh parsley, 0.25 cup fresh basil
