The purpose of sautéing seafood is to
give it a crisp, lightly browned crust. The seafood is cooked in butter
(clarified is best because it doesn't burn over high heat) or oil over
intense heat, so that the outside of the food browns quickly before the
inside overcooks. It's easiest to cook small shellfish such as scallops or
shrimp by tossing them in a pan with sloping sides; the sloping sides make
the tossing motion easier. Whole fish, fish fillets, and steaks would fall
apart if tossed that way, so they are browned on one side and then
carefully turned with a spatula.
Fish steaks, thick fillets, and small
thin whole fish such as sole or trout are the simplest to sauté because
they cook through in about the same amount of time it takes the exterior
to brown. Thin fillets, especially from fragile fish such as flounder,
fall apart if overcooked by even a second, so watch them carefully.
It is advisable to cook most fillets
with the skin on, because the skin holds the fillet together, tastes
deliciously crispy, and looks good. But skin tends to stick, so use a
nonstick pan or a well-seasoned skillet. Fish skin also contracts when
hot, causing the fillet to curl. To prevent curling, start the fillet
flesh side down, cooking it for a minute or two to allow the flesh to
contract. Then turn the fillet skin side down and press down with the back
of a spatula as it cooks to prevent it from curling and to keep the skin
in contact with the bottom of the pan so its entire surface browns.