You don’t get the grill or stove warm enough
The pan or grill should be searing hot. When cold fish proteins come in contact with hot metal, they form chemical bonds that are extremely tough to break. It’s why you end up leaving part of the fish behind when you flip it. If you’re cooking your fish on the grill or stovetop, be patient. “Put your pan on the stove and turn the burner on medium heat for three to five minutes before placing your fish,” says Giuseppe Tentori, executive chef and partner of a seafood restaurant. When the pan or grates are extremely hot, the fish is easier to flip.
You cook it for too long
Cooking fish too long will dry it out and cause it to lose its natural flavours. A good rule of thumb: Measure the fish at its thickest point and cook for 10 minutes per 2.5cm, flipping halfway through. The flesh should feel firm and turn from translucent to opaque or white, but still be slightly translucent in the middle. “Take it off when there’s just that little bit of translucency left in the middle,” says Randy Hartnell, former fisherman and founder of Vital Choice, a website that sells fresh seafood. “You can apply this tip to almost any type of fish. If it’s almost done, it’s done.” For salmon, look for white lines to stand out. “When salmon is almost done, some of the proteins – which are a white colour – will begin to leak out of the fish because they’ve coagulated,” says Tentori.
You touch it too much
Poking at your fish will cause its crunchy outer layer of skin, which traps delicious juices inside the fish, to fall apart as it cooks. Keep flipping to a minimum, and never use tongs. “Use one or two rubber or metal spatulas, or even a spoon, to flip it,” says Tentori. If fish is ready to be flipped, you will be able to easily slide a spatula underneath it. If you try prying it off too early, its crispy layer will stick to the pan.