Remove salmon from packaging. place on a large cutting board lined with paper towel. Remove any pin bones fro the spine of the fish with tweezers. To find bones, run your fingers gently over the fish flesh. A good fish monger will remove the scales but be sure to check and remove any that remain.
Pat the skin and flesh dry with more paper towels. Place the fish uncovered, skin side up in refrigerator for 10-15 minutes. This will dry the fish to achieve perfect crispy skin.
Slice the fish into 4 equal portions. Right before cooking, salt the fish. Adding salt too early will release the fishes natural moisture and the skin will not get crisp.
Add enough oil to completely cover the bottom of a hot cast iron pan (about ¼ cup). Place the salmon into the pan skin side down. Using a spatula, gently press the fish to enable the skin to cook evenly. Cook 7 minutes without turning. Flip the fish over and cook 1 minute longer. Flip one more time to reheat the skins before plating. This method is tried and true-perfect crispy skins every time.