Brown the chorizo. Heat 2 Tbsp extra virgin olive oil in a large Dutch oven over medium-high heat. Add the chorizo and cook, stirring occasionally, until light browned and the edges crisp, 2-3 minutes. Use a slotted spoon to transfer the sausage to a plate (leave the rendered fat in the pot).
Sauté the aromatics. Reduce the heat to medium. Add the onion, leek, and potatoes to the pot and season with a pinch of Kosher salt. Cook, stirring occasionally, until the onions and leeks are soft and the potatoes are starting to turn tender, 8-10 minutes. (If the pot looks dry at any point, drizzle in a touch more olive oil.)
Bloom the garlic and spices. Add the garlic, tomato paste, and smoked paprika. Stir constantly until fragrant and the tomato paste deepens slightly in color, 1-2 minutes.
Deglaze with wine. Pour in ⅓ cup dry white wine and scrape up any browned bits from the bottom of the pot. Simmer until slightly reduced, about 1-2 minutes.
Build the broth. Stir in the diced tomatoes, then return the chorizo (plus any accumulated juices) to the pot. Add the fish stock (or broth/clam juice), saffron threads, oregano sprigs, and bay leaf. Bring to a boil over medium-high heat, then reduce to a lively simmer and cook until the broth is flavorful and slightly reduced, 4-5 minutes.
Season the fish. While the soup simmers, pat the fish dry, then season with 1 tsp kosher salt, ¼ tsp freshly ground black pepper, and fresh lime zest.
Cook the fish gently. Nestle the fish into the simmering soup in an even layer. Cover with a tight-fitting lid and cook until the fish is opaque and flakes easily, 5-7 minutes, depending on thickness. (Avoid stirring—just gently press pieces under the liquid if needed so they cook evenly.)
Finish + serve. Remove and discard the oregano and bay leaf. Taste the broth and adjust seasoning with more salt and pepper as needed. Ladle into shallow bowls, drizzle with a little good olive oil, and garnish with parsley, cilantro, or sliced scallions. Serve hot with crusty bread and lime wedges for squeezing. Enjoy!