Adapted from Giada DeLaurentiis' Everyday Italian. Serves 8.
3 Tbsp olive oil
1 large fennel bulb, thinly sliced (a mandoline works well for this, if you have one)
1 onion, chopped
2 large shallots, chopped
4 large garlic cloves, finely chopped
1/2 tsp dried crushed red pepper flakes, or more to taste
1 large squirt of tomato paste from a tube (2 Tbsp, more or less)
1 26-oz box Pomi chopped tomatoes, or equivalent canned or fresh tomatoes with juice
1-1/2 cups dry white wine
3 cups chicken stock or store-bought low-sodium chicken broth
2 8-oz bottles clam juice
1 bay leaf
1 lb littleneck clams, scrubbed
1 lb mussels, scrubbed and debearded
1 lb raw "large" shrimp (26-30 size), peeled and deveined
1/2 lb halibut or mako shark, cut into 2-inch chunks
1/2 lb cod (the thick loin) or scrod, cut into 2-inch chunks
1/2 lb salmon (skinless fillet), cut into 2-inch chunks
2-3 Tbsp rough-chopped flat-leaf parsley, for garnish
Heat the oil in a very large nonreactive stockpot over medium heat. Add the fennel, onion, shallots, and salt, and sauté until the onion is translucent, about 10 minutes. Add the garlic and red pepper flakes, and sauté 2 minutes. Stir in the tomato paste, canned tomato with the juices, wine, chicken stock, clam juice and bay leaf. Cover, and raise the heat just until the soup comes to a low boil. Reduce the heat to medium-low. Cover and simmer until the flavors blend, about 30 minutes. (Can be made ahead up to this point; refrigerate or freeze.)
Add the clams to the cooking liquid. Cover and cook 10 minutes or until the clams begin to open. Add the mussels, shrimp and fish. Simmer gently until the fish and shrimp are just cooked through, and the mussels are open, about 5 minutes (discard any clams and mussels that do not open). Season the soup to taste, with more salt and red pepper flakes. Top with parsley. Ladle the soup into bowls, and serve.