3 Tbsp extra-virgin olive oil, plus more for drizzling
2 leeks, white and light green parts only, thinly sliced
1 onion, cut into ¼” dice
1 fennel bulb—fronds reserved, bulb cored and cut into ¼” dice
4 garlic cloves, 3 coarsely chopped
2 tomatoes, cut into ½” dice
2 bay leaves
Pinch of saffron threads
5 cup store-bought fish stock
3 Yukon Gold potatoes (1 ½ lbs), peeled and cut into ½” dice
¼ tsp cayenne pepper
1 dz littleneck clams, scrubbed
1 dz mussels, scrubbed and de-bearded
2 lb skinless Pacific rockfish fillets, cut into 1 ½” pieces
- In a very large, deep skillet, heat the 3 tablespoons of olive oil. Add the leeks, onion, fennel and chopped garlic and cook over moderate heat until translucent, about 5 minutes. Add the tomatoes and cook until they begin to break down, about 5 minutes. Add the bay leaves and saffron, and bring to a boil. Add the fish stock and bring to a simmer. Cook over low heat until the vegetables are very tender, about 20 minutes. Discard the bay leaves.
- In a food processor, pulse the vegetables and broth to a coarse puree. Strain through a fine sieve set over the skillet.
- Add the potatoes and cayenne pepper to the broth and bring to a simmer. Cook over moderately high heat until the potatoes are just tender, about 10 minutes; season with salt and pepper. Add the clams and mussels, cover and cook over moderate heat until they just begin to open, about 3 minutes. Add the rockfish, cover and simmer until the clams are open and all the fish is cooked through, about 4 minutes.
- Sprinkle with fennel fronds and serve immediately.