In a small bowl, mix together the Italian seasoning, garlic powder, ½ teaspoon kosher salt, pepper and red chili flakes (if desired).
Cut the cod into 4 even pieces and place in a medium bowl. Sprinkle the herb mixture over the cod and turn to coat.
Heat 2 teaspoons olive oil in a large nonstick skillet set over medium-high heat. Add the cod and cook until seared a bit, about 2 minutes per side. Transfer the fish to a plate.
Reduce the heat to medium and carefully wipe out the skillet with a paper towel.
Heat the remaining 2 teaspoons olive oil in the skillet, then add the onion and carrots. Cook until the vegetables are starting to soften, stirring occasionally, about 5 minutes. Add garlic and oregano and cook for 30 seconds.
Pour in the crushed tomatoes. Bring the mixture to a boil, then reduce the heat so that the mixture is simmering. Cook for 10 minutes, stirring occasionally. Season with the remaining ¼ teaspoon salt, or to taste, and stir in the parsley.
Nestle the pieces of cod into the sauce so that the sauce comes up the sides of the fillets. Cover and cook until fish is just cooked through, 5 to 8 minutes.