Coat fresh tomatoes in olive oil and either roast in a shallow baking dish at 450° F for 45 minutes or keep on a hot grill until skin begins to split and deepen in color.

Meanwhile, in a large heavy-bottomed pot or enameled Dutch oven, sauté onion, shallots, and fennel in olive oil over medium heat until softened and onions become translucent, approximately 10 minutes. Sprinkle with sea salt, Basque chili powder or smoked paprika, and minced or roasted garlic, stirring until fragrant, 1–2 minutes.

Roughly chop roasted tomatoes and stir into the onion base along with the canned tomatoes and their juice, tomato paste, stock, red wine, and bay leaves. Bring to a boil, then reduce heat to medium low, cover and simmer for 30 minutes, stirring occasionally.

Remove lid after 30 minutes and add clams to the broth, cooking until they begin to open their shells. At this point, toss in the shrimp, salmon, and halibut, simmering until clam shells are fully open and the fish has cooked through. Discard any clams with unopened shells. Season with additional salt, to taste and serve topped with red pepper flakes.

* If roasting tomatoes in the oven, consider tossing garlic cloves in oil, still encased in their papery cover, and adding them to the tomato pan for 20 minutes to soften prior to squeezing them from their skin into the stew to create a caramelized taste.