Substituting fish for red meat once or twice a week is a quick way to make your diet healthier. Most kinds of seafood cook quickly, so they fit with even the busiest of lifestyles. The only drawback is that fish is a supremely perishable ingredient, so keeping it on hand for impulse meals is problematic. One solution to this conundrum is frozen fish. Its quality is very high, it's always there when you need it, and -- when you're in a hurry -- it can be baked from frozen.
Freshness, Freezing and Quality
Some cooks have a strong prejudice against frozen seafood and consider it innately inferior. If you can buy it fresh directly from the boat or the processing plant, that's probably true. However, the quality of fish degrades rapidly once it's out of the water. Unless you've taken some pains to cultivate friendly relations with your neighborhood fishmonger, the fillets in your shopping basket could be several days old. Frozen fish, on the other hand, is flash-frozen on the boat or in the processing plant almost as soon as it stops moving. This preserves its fresh flavor, and the high-speed freezing process minimizes any effect on its texture.
Choosing Your Product
The frozen section of your local store probably has a wide selection of seafood, but some are better choices than others. If you want the option of cooking from frozen, avoid fillets that are frozen together into a solid "brick" of fish. Instead, buy IQF-- individually quick frozen -- fish or fillets, which can be taken out individually. If a package is labeled IQF but the fish are stuck together, don't buy it. That means it has thawed and refrozen, and may no longer be food-safe. Avoid very thick fillets or large whole fish, which take longer to cook and are best thawed first.
Preparing Frozen Fish
When you want to prepare a meal of frozen fish, remove the appropriate number of fillet portions or small whole fish from your freezer, then reseal the package. Rinse the fish thoroughly under cold running water while your oven is preheating. Many processors protect the fish against freezer burn by coating it with a thin glaze of ice, which must be removed. Even unglazed fish often accumulates a coating of frost, which should be removed to avoid any "off" flavors. Pat the fish dry on clean paper towels before you go on to baking it.
In the Oven
You have two main options for baking frozen fish. To dry-bake it, arrange the portions on a sheet pan lined with foil or parchment paper, then brush or spray them lightly with oil. Bake them at 425 to 450 degrees Fahrenheit for 12 to 15 minutes. Thick fillets might take a few minutes longer and benefit from being turned midway through cooking. A second alternative is to bake your fish in a sauce, such as a tomato sauce made with fresh ripe tomatoes, to help moisten and flavor it. Arrange the portions in a baking dish, cover them with the sauce, and bake in a moderate oven at 325 F or 350 F until the fish is just opaque at the thickest point.