Heat the olive oil in a large, heavy saucepan over medium heat. Add the garlic and spices. Cook, stirring, for 30 seconds.
Whisk in the tomato sauce and kosher salt. When the mixture starts to boil, add the fish pieces, spooning the sauce on top to cover them. Bring back to a gentle boil.
Cover (use heavy-duty foil if your skillet does not come with a lid), lower the heat to medium-low, and cook until the fish is cooked through, for about 15 minutes.
Garnish with parsley and serve.
Video
Notes
While you can make this recipe with regular canned tomato sauce, I prefer to use strained tomatoes by one of two Italian brands - Pomi or Bionature. These tomatoes are smooth, flavorful, and sweet. A domestic US tomato sauce will be more acidic.
You can keep the leftovers in the fridge, in an airtight container, for up to 3 days. Reheat them very gently, covered (to prevent splatters), in the microwave at 50% power.