Rinse the cod in cold water and remove any bones. Pat fish dry with a paper towel.
Rinse parsley and dry it before chopping the leaves. Set aside. Slice up the garlic.
If using fresh tomatoes, rinse, core, and peel them (optional). Cut the tomatoes into 1-inch wedges and remove the seeds. (If using canned tomatoes, just use four tomatoes from the can. Cut them up with a fork and drain the juice.)
Heat one tablespoon of the olive oil in a 12-inch skillet on mediump-high. Add the garlic and saute it for two minutes until fragrant and sizzling. Then add the cod and top with tomatoes, 2 tablespoons of parsley, pepper and ¼ teaspoon salt. Pour ¼ cup of olive oil on top and bring the pan to a boil.
When boiling, put the heat on low and cover the pan. Cook until the cod can be flaked with a fork. The cooking time will depend on the thickness of your fish, but start checking after 10 minutes of being covered. Do not flip the fish. When the cod is just about done, add olives for the last minute of cooking.
When the cod is done, turn off the heat. If desired, you can let the fish sit in the covered pan for a few minutes until you're ready to serve it. (The cod can stay in the pan for up to two hours, but uncover it after a few minutes, so it doesn't continue steaming in the pan. Reheat if desired.) Garnish with a tablespoon of parsley and add any extra salt needed before serving.
Refrigerate leftovers for up to four days. I would not recommend freezing this.
Fish: Use Atlantic cod, Pacific cod, scrod, haddock, pollock or any sturdy white fish, such as halibut. It's best to use thick fish fillets, so the tomatoes have time to cook down. If you're starting with frozen cod, let it thaw first.Tomatoes: If you use fresh tomatoes, it's best to peel them first, so you don't end up with pieces of tomato skin in the final dish. For convenience, I prefer using four whole, peeled tomatoes from a 28-ounce can.Then, I use the remaining canned tomatoes to make Italian Green Beans to go with the cod. You also could use the remaining tomatoes to make Italian Sauteed Mushrooms or a tomato sauce for pasta.