Baccalà is salted codfish, widely found in the Mediterranean. In dried form, it is called stoccafisso, or stockfish. Both versions must be soaked in cold water for at least 24 hours. Baccalà needs the water frequently changed to remove the salt as it dissolves, and is sometimes left to soak under a slow stream of water. In zimino denotes fish (cod, eel, or squid) cooked with olive oil and greens, usually spinach or Swiss chard.
Soak the salted cod in cold water for 24 hours, draining and adding fresh water every 4-6 hours. Drain well. Cut the softened cod into 2-inch chunks and set aside.
In a large, heavy saucepan, heat the oil over medium heat, and sauté the carrot, celery, and onion for 3-4 minutes, or until softened. Add the pepper flakes and tomato sauce and heat for 2-3 minutes. Add the chard and cook for about 5 minutes, or until wilted. Decrease the heat to medium, cover, and cook for 15 minutes, or until the cod is fork-tender. Season with salt and pepper to taste, garnish with parsley, and serve at once.