Makes 6 servings

All over the Mediterranean, fish soups are made from the day?s catch. I enjoyed an especially memorable heaping bowl earlier this summer in Marseille, but each region has its own different and wonderful variation. Traditionally, fish heads are simmered in seasoned water to make fish stock. For quicker and easier preparation, substitute canned chicken stock.

2 tablespoons olive oil 1 cup finely chopped onion 4 cloves garlic, minced 2 large tomatoes, peeled (see Tip) and coarsely chopped 1 small red chili, finely chopped, or to taste (or 1/8 teaspoon red pepper flakes, or to taste) 1 teaspoon saffron threads, crushed 1 tablespoon hot water One 49 ½-ounce can chicken broth 3 small red potatoes, cut into ½-inch cubes 1 carrot, coarsely chopped 1 rib celery, coarsely chopped ¼ cup finely chopped flat-leaf parsley ½ teaspoon freshly ground pepper, or to taste ½ teaspoon salt, or to taste 8 ounces firm fish (such as sea bass, mackerel, or monk fish), remove and discard skin, cut flesh into 1-inch chunks 8 ounces sea scallops 4 ounces medium-size shrimp, shelled and deveined Minced fresh flat-leaf parsley for garnish

Heat the oil in a Dutch oven over medium-high heat. Add the onion and garlic; cook, stirring occasionally, until tender, about 3 minutes.

Meanwhile, mix the saffron with the hot water; set aside.

Reduce the heat to medium; add the tomatoes and red chili (if using). Cook, stirring occasionally, until the tomatoes are broken and softened, about 5 minutes.

Stir in the chicken broth and increase the heat to high; when the liquid comes to a boil, reduce the heat to medium-high. Stir in the saffron-water mixture and the potatoes, carrot, celery, parsley, pepper, salt, saffron, and red pepper flakes (if using). Cover and cook until the vegetables are tender, about 10 minutes. Taste and adjust the seasoning.

Stir in the fish, scallops, and shrimp. Cover and cook until the fish is done, about 5 minutes. (Take care not to overcook.)

Advance preparation

The broth with vegetables can be prepared up to 2 days in advance; cover and refrigerate. Reheat, add and cook the seafood just before serving.