Heat the olive oil over medium heat in a heavy-bottomed pot large enough to hold all the ingredients. Sauté the shallots for 2 to 3 minutes without browning, then add the garlic and continue to cook for an additional 2 minutes or until the garlic is softened but not browned. Add the celery and potatoes and sauté for another 2 to 3 minutes. Pour the fish stock and wine into the pot. Add the thyme sprigs and simmer for 5 to 6 minutes. The potatoes should be almost cooked through. Add salt and pepper to your taste.
Lower the snapper, grouper, and salmon into the broth. Cover and cook for 1 minute. Then add the scallops and mussels. Cover again and cook 2 to 3 minutes-just until the mussels open.
Ladle the broth and fish into 6 large, heated bowls. Remove the thyme sprigs. Sprinkle the green onion, parsley, and sliced tomatoes among the bowls. Top each bowl with 3 baguette toasts spread with Romesco Sauce and a healthy drizzle of olive oil.
Fish Stock (or use good store-bought stock)
3 lbs. (1.35 kg) non-oily fish bones and fish heads
1 Tbsp. (15 mL) vegetable oil
1 small onion, chopped
1 celery stalk, chopped
1 bay leaf
1 carrot, peeled and chopped
10 cups (2.4 L) cold water
½ cup (120 mL) dry white wine
10 white peppercorns
1 bouquet garni of 6 stalks of parsley, 2 stalks of thyme
Rinse the fish bones and heads, making sure there is no blood left on them. Heat the oil in a large stockpot. Add the onion, celery, bay leaf, and carrot. Sauté for 3 to 4 minutes. Do not let the vegetables brown. Add the fish bones and toss with the vegetables. Cook for another 2 to 3 minutes.
Pour in the cold water and wine and drop in the peppercorns and bouquet garni. Cover and bring to a simmer. Skim off any froth. Simmer for 40 minutes. Taste. If you want a more concentrated stock, remove the lid and simmer for 10 more minutes. Drain the stock through a sieve, pressing on the vegetables and fish bones. Freeze any leftover stock.
Photo by Chris Freeland.