In a large heavy-bottomed pot or Dutch oven, combine fish or seafood stock, white wine, water, crushed tomatoes, and tomato paste. Stir to dissolve the paste into the liquids.

Add bay leaves, thyme sprigs, whole peppercorns, and 1 teaspoon of the salt. Bring the mixture to a gentle simmer over medium heat, then reduce to low and keep at a bare simmer while you prepare the aromatics (about 10 minutes).

Aromatics & Vegetables

Meanwhile, heat olive oil and butter in a large sauté pan over medium heat until butter foams.

Add the diced onion, celery and carrots. Sauté, stirring occasionally, until the vegetables are softened and the onion is translucent, about 6–8 minutes.

Add diced red pepper, sliced fennel (if using), red pepper flakes and the remaining 1 teaspoon salt. Cook 3–4 minutes more until peppers soften.

Add the minced garlic and cook 30–60 seconds until fragrant, being careful not to brown the garlic.

Transfer the cooked aromatics to the simmering broth. Stir to combine and simmer together for 10 minutes to let flavors meld.

Seafood

Increase heat under the pot so broth returns to a gentle simmer (not rolling boil). Taste and adjust seasoning with salt if needed.

Add the firm white fish pieces first. Gently stir and simmer for 3–4 minutes until fish is beginning to become opaque but not fully cooked.

Add the clams and mussels, pushing them into the broth so they sit with the hinge side down. Cover the pot and cook 4 minutes.

Uncover and add the shrimp and scallops. Stir gently, cover, and cook 2–3 minutes more until shrimp are pink and opaque, scallops are firm, and all shellfish have opened. Discard any mussels or clams that remain closed.

If the broth has reduced too much, add up to 1/2 cup water or stock to reach desired consistency and bring back to a simmer briefly.

Finishing & Garnish

Remove the pot from the heat. Fish out and discard bay leaves, thyme stems, and whole peppercorns if you prefer a smoother broth.

Stir in lemon juice, chopped parsley, chopped basil (if using), and drizzle with extra-virgin olive oil. Taste and finish with freshly ground black pepper and additional salt if necessary.

Ladle the soup into large bowls, distributing fish, shrimp, clams, mussels and scallops evenly. Serve with lemon wedges and slices of crusty bread for dipping.