A quick braise is the best way to keep lean white fish like cod incredibly moist. The fillets cook in a gently simmering sauce, basted by aromatic steam in the covered pan. This is an ideal method for other lean white fish that can dry out easily, such as halibut, haddock, striped bass, or grouper.
How to Make It
Heat oil in a 12-inch high-sided skillet over medium-high. Add leek and fennel; cook, stirring often, until softened, about 7 minutes. Add tomato paste and garlic; cook, stirring constantly, until fragrant, about 1 minute. Stir in clam juice, tomatoes, olives, 1/2 cup water, and 1/4 teaspoon salt; bring to a boil. Reduce heat to medium-low; simmer until slightly reduced, about 10 minutes. Adjust heat as needed to maintain a very gentle simmer.
Sprinkle cod with remaining 1/4 teaspoon salt. Nestle fish into tomato mixture; cover and cook until fish is done, about 10 minutes. Serve cod and tomato mixture over couscous. Garnish with parsley and lemon, if desired.