Slow and Steady Wins the Salmon Race
The best way to cook frozen salmon is to thaw it before cooking. If you leave it out overnight in the refrigerator or put it in the fridge before you leave for work in the morning, it should be ready to poach, saute or bake by the time you get home. That said, very gentle poaching is an alternative that produces good results when you have no choice but to cook the fish while it’s still frozen.
Pros and Cons
Saving time is of course the best reason to cook salmon directly in its frozen state. But you won't be able to pick out those pesky bones before cooking, and trying to do that after the fish is cooked results in smashed and broken fillets and mangled steaks. What's more, your cooking options are limited. Sauteing won't work with frozen fish because the outside of the fish overcooks before the inside cooks through.
Giving frozen salmon help in thawing gets the job done in 5 to 10 minutes. Place the salmon in a sealable plastic bag and submerge it in hot tap water, using a plate to weigh down the fish if it wants to bob up. If you have one large piece of salmon, remove it from the bag after 5 minutes and cut it into separate fillets to speed up thawing. You'll know the salmon is completely thawed when you can bend it back and forth from the middle.
Best Cooking Method
Poaching frozen salmon slowly results in tender, succulent fillets and steaks. When you begin cooking in cold water, the outside and inside of the fish thaw before the outside flesh actually begins to cook. Place the salmon in a pot with enough cold water to cover it, and set the heat to high. Keep your eye on the water, and turn the burner to low when the water begins to quiver but before any bubbles break the surface. Cover the pot, and let the salmon poach gently for 25 to 35 minutes depending on the size of the pieces.
When your poached salmon flakes easily when you probe it with a fork, or when it reaches 115F on an instant-read food thermometer, spoon it out with a slotted spatula and set it on paper towels or a clean dishtowel to absorb excess water. Serve poached salmon hot, at room temperature or chilled, with a splash of lemon juice, salt and ground black pepper for a minimalist treatment when the fish is hot, or with a dill or cucumber yogurt sauce for room-temperature or chilled fish.