Place the pan on the stove and put the salmon filet in it skin side up. Let it sear for 3 to 4 minutes
Flip the fish and reduce the heat a little. Cook to an internal temperature of approximately 52 Celcius (125 Fahrenheit) approximately 10 minutes
Serve immediately with your favourite sauce
Notes
I found this recipe in a book of americas test kitchen "Cook it in Cast Iron" and adapted to my own needs. The trick of preheating the pan in the oven and searing the fish worked really well for me. You can serve the salmon with a sauce of you choosing or some lemon slices.