How to poach fish | Flavor
Put away the hot pan and away from the fiery grill. While writing my book, The Pacific Northwest Seafood Cookbook, I’ve learned that most people, when given a fish, tend to turn to the same cooking methods they use to prepare meat. But learning how to poach fish gives you a simple, indulgent, and versatile way to prepare this leaner and much more delicate ingredient. Since the correct temperature of poaching liquid is only slightly higher than the temperature of perfectly cooked fish, this method reduces the risk of overcooking. The technique also works well for just about any type of fish, from firm white varieties like cod and tilapia, to oilier fish like salmon, to shellfish like shrimp and lobster. You can poach fish in a wide range of different liquids and serve poached fish with all types of sauce or without any sauce.
What do you need
BEFORE YOU START
You can poach any type of fish in just about any type of liquid, but I recommend leaving the fish whole after you’ve mastered filleting poaching. You can use fillets with or without skin (but be aware that poaching tends to produce unappetizing and somewhat slimy skin). Many poaching recipes suggest using a quick, light broth called court-bouillon, but I suggest starting with an even simpler liquid. Any moderately salty broth diluted with wine works well, as does salted milk. Poaching in oil or butter works especially well for lean fish like halibut or albacore. (Pro tip: For incredible flavor, brown the butter; just be sure to bring it back to poaching temperature before adding your fish.)
STEP 1: Heat your liquid until it simmers gently.
Pour enough liquid into a wide saucepan or deep skillet to just cover the fillets (if necessary, test this before heating the liquid). Place the pan over medium heat until it simmers, then turn the heat down so the liquid keeps some movement but doesn’t quite produce the bubbles that indicate simmering. Oil and butter produce fewer bubbles than water and water-based liquids, so you’ll need to use an instant-read thermometer to check the temperature of these fat-based poaching liquids. You’re going for 140 to 160 degrees Fahrenheit. Don’t worry too much about maintaining an exact temperature, as that level of precision is difficult on most stoves.
STEP 2: Gently slip the fish into the liquid and cook.
Place the fillet on the fish spatula and slide it gently into the liquid. Repeat with as many fillets as needed without crowding the pan. The more fillets you cook at a time, the longer they will take to cook, as the poaching liquid will take longer to return to poaching temperature. Keep an eye on the liquid as it cooks, moderate the heat to make sure it doesn’t go over 160 degrees Fahrenheit. (But again, this is a forgiving method: if the liquid starts bubbling, your fish will be fine; just turn the heat down).
STEP 3: Once cooked, remove the fish from the pan.
The cooking time for fish depends on the temperature of the liquid, the thickness and the type of fish. For a one-inch-thick cod fillet in broth, allow about 7 minutes. For a thick, buttery tuna steak, maybe closer to 10. If you poke the fillet with a utensil, the flesh should be very soft and just starting to flake. For ultra-thin fish, you can remove them from the liquid once the flesh becomes opaque. But the best way to find out is to use your instant-read thermometer. Most fish is cooked to medium doneness at around 135 degrees Fahrenheit (slightly earlier for tuna or shrimp). Remember that your liquid isn’t much hotter than this, so the fish is unlikely to be overcooked – that’s the magic of poaching! Using your fish spatula, very carefully lift the fish out of the pot, as tender fish can fall apart easily.
STEP 4: Sauce—or not—as desired.
If you’re poaching black cod (sablefish) in browned butter, you probably don’t need to add any sauce. If you made albacore in olive oil, you can make a Niçoise salad. Top poached fish with almost any sauce or make a sauce with your poaching liquid. The classic court-bouillon becomes a velouté when you reduce the liquid by half and whip it into a light roux.
Knowing how to poach fish takes the guesswork out of cooking any type of fish, and the low-temperature method makes it difficult to boil. Using a light broth is one of the healthiest cooking methods, while poaching in butter is one of the tastiest, but either way, or with any other combination of fish and liquid cooking, the same simple process works.