Cooking time will vary greatly depending not only on the cut of fish but also the cooking method. In general, your cod will be done when it reaches an internal temperature of 54°C (130°F), regardless of cooking method. Here are some times/temperatures that work for me:
- Sous Vide: 10 minutes or more at 56°C, followed by a quick broiling/grilling/blow torch.
- Baking (thick fillets): 15–20 minutes at 218°C (425°F).
- Baking en papillote: 15 minutes at 232°C (450°F).
- Deep Frying: 7–8 minutes at 190°C (375°F).
- Steaming: 6 minutes.
- Poaching: I like to add the fish to the cooking liquid while the liquid is room temperature. I bring it to a simmer, and then turn the heat to low, cover, and cook for about 15 minutes.
- Pan Frying: This isn't quite as popular a method as the above for cooking cod, however, if you want to do it, I would recommend cooking it on high heat, flipping once the opaqueness has reached about halfway up the side of the fillet.
Basically, it doesn't matter which method you use as long as your cod ends up with an even internal temperature of around 54°C (130°F).