2 tablespoons extra-virgin olive oil
1 shallot, thinly sliced
Kosher salt and freshly ground black pepper
1 garlic clove, thinly sliced
½ teaspoon crushed red pepper flakes, or more, as desired
Two 14-ounce cans crushed tomatoes and their liquid
1 cup low-sodium vegetable stock (or water)
Four 5-ounce cod fillets
1 cup parsley or basil leaves and fine stems, roughly chopped or torn, for sprinkling
Toasted crusty bread, for serving
1. Heat the oil in a wide, shallow skillet over medium heat until shimmering. Add the shallot and salt, stirring until softened, about 3 minutes. Add the garlic and pepper flakes, stirring until fragrant, about 30 seconds more. Pour in the tomatoes and stock and raise the heat to bring the mixture to a boil. Lower the heat to a simmer, stirring occasionally, and season with salt and pepper. Let it cook until the tomatoes lose their tinned taste and the liquid reduces slightly, 8 to 10 minutes
2. Season the fish with salt and pepper and add to the sauce, adjusting the heat to maintain a gentle simmer. Cook, spooning the sauce over the fillets occasionally, until the fish is opaque and easily flakes when touched, about 5 minutes. If they are not fully submerged, turn them over halfway. (Thick fillets will take a little longer.)
3. Divide the fish between serving bowls and spoon the tomato sauce on top. Finish with pepper and parsley and serve with the bread for dipping.
NOTE: To add more heat to the dish, you can stir in ½ to 1 tablespoon harissa when adding the shallots and garlic.