How to Make It
In a large saucepan, heat the oil over moderate heat. Add the garlic and cook, stirring, for 1 minute. Add the canned tomatoes, fresh tomato, salt, and red-pepper flakes and bring to a simmer. Simmer the sauce until thick, about 30 minutes.
Add the cod and 2 tablespoons of the parsley to the sauce. Bring back to a simmer and continue simmering until the fish is just done, 1 to 2 minutes. Break the fish into small pieces with a spoon.
Meanwhile, in a large pot of boiling, salted water, cook the penne until just done, about 13 minutes. Drain. Toss with the sauce. Top the pasta with the remaining tablespoon parsley.
Variation To make this dish without a trip to the fish market, substitute two six-ounce cans of drained tuna for the cod. Stir it into the tomato sauce and warm for about a minute before tossing with the pasta.
Test-Kitchen Tip To peel the fresh tomato quickly, make double use of the pasta-cooking water. Bring a pot of water to a boil, core the tomato, and drop it into the water for fifteen seconds. Using a slotted spoon, remove the tomato from the water, peel, and chop it. Then you've got boiling water ready for the pasta.